LED tube lamp

ABSTRACT

An LED tube lamp includes a lamp tube, an LED module, a power supply module, a micro switch, and an actuator. The lamp tube has pins for receiving an external driving signal. The power supply module is configured for supplying power to the LED module. The micro switch is coupled to the power supply module. And the actuator is configured to cause the micro switch to change to a closed-circuit position to allow the power supply module to supply power to the LED module for emitting light. When the LED tube lamp is properly installed into a lamp holder, the micro switch closes to electrically connect the power supply module to an external driving signal.

RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patent application Ser. No. 15/055,630, filed Feb. 28, 2016, in the United States Patent and Trademark Office, the entire contents of which are incorporated herein by reference, and which claims the benefit of priority under 35 U.S.C. §119 to the following Chinese Patent Applications, filed with the State Intellectual Property Office (SIPO), the entire contents of each of which are incorporated herein by reference: CN201510104823.3, filed Mar. 10, 2015; CN201510134586.5, filed Mar. 26, 2015; CN201510133689.x, filed Mar. 25, 2015; CN201510173861.4, filed Apr. 14, 2015; CN201510193980.6, filed Apr. 22, 2015; CN201510372375.5, filed Jun. 26, 2015; CN201510284720.x, filed May 29, 2015; CN201510338027.6, filed Jun. 17, 2015; CN201510315636.x, filed Jun. 10, 2015; CN201510406595.5, filed Jul. 10, 2015; CN201510486115.0, filed Aug. 8, 2015; CN201510557717.0, filed Sep. 6, 2015; CN201510595173.7, filed Sep. 18, 2015; CN201510530110.3, filed Aug. 26, 2015; CN201510680883.X, filed Oct. 20, 2015; CN201510259151.3, filed May 19, 2015; CN201510324394.0, filed Jun. 12, 2015; CN201510373492.3, filed Jun. 26, 2015; CN201510482944.1, filed Aug. 7, 2015; CN201510499512.1, filed Aug. 14, 2015; CN201510448220.5, filed Jul. 27, 2015; CN201510483475.5, filed Aug. 8, 2015; CN201510555543.4, filed Sep. 2, 2015; CN201510724263.1, filed Oct. 29, 2015; and CN201610050944.9, filed Jan. 26, 2016. In addition, this application claims the benefit of priority under 35 U.S.C. §119 to the following Chinese Patent Applications: CN201510378322.4, filed Jun. 29, 2015; CN201510428680.1, filed Jul. 20, 2015, and CN201510645134.3, filed Oct. 8, 2015, the entire contents of each of which are incorporated herein by reference. In addition, Chinese Patent Application CN201510075925.7, filed Feb. 12, 2015, and Chinese Patent Application CN201510136796.8, filed Mar. 27, 2015 are also incorporated by reference herein in their entirety.

TECHNICAL FIELD

The disclosed embodiments relate to LED lighting apparatuses or devices. More particularly, the disclosed embodiments relate to an LED tube lamp with a capability of preventing or reducing the likelihood of an electronic shock on a user who is installing the LED tube lamp into a lamp holder, and its structures.

BACKGROUND

Light emitting diode (LED) lighting technology is rapidly developing to replace traditional incandescent and fluorescent lighting. LED tube lamps are mercury-free in comparison with fluorescent tube lamps that need to be filled with inert gas and mercury. Thus, it is not surprising that LED tube lamps are becoming a highly desirable illumination option among different available lighting systems used in homes and workplaces, which used to be dominated by traditional lighting options such as compact fluorescent light bulbs (CFLs) and fluorescent tube lamps. Benefits of LED tube lamps include improved durability and longevity and far less energy consumption; therefore, when taking into account all factors, they are typically considered a cost effective lighting option.

Typical LED tube lamps each have a variety of LED lamp components and driving circuits. The LED lamp components include LED chip-packaging elements, light diffusion elements, high efficient heat dissipating elements, light reflective boards and light diffusing boards. Heat generated by the LED lamp components and the driving elements is considerable and mainly dominates the illumination intensity such that the heat dissipation should be properly disposed to avoid rapid decrease of the luminance and the lifetime of the LED lamps. Problems including power loss, rapid light decay, and short lifetime due to poor heat dissipation tend to be key factors in consideration of improving the performance of the LED illuminating system. It is therefore one of the important issues to improve on the heat dissipation aspects of the LED products. Nowadays, most LED tube lamps use plastic tubes and metallic elements to dissipate heat from the LEDs. The metallic elements disposed to dissipate heat from the LEDs may be made of aluminum.

Current ways of using LED lamps such as LED tube lamps to replace traditional lighting devices (referring mainly to fluorescent lamps) include using a ballast-compatible LED tube lamp. Typically on the basis that there is no need to change the electrical or conductive wirings in the traditional lamps, an LED tube lamp can be used to directly replace e.g. a fluorescent lamp. But an LED is a nonlinear component with significantly different characteristics from a fluorescent lamp. Therefore, using an LED tube lamp with an electronic ballast impacts the resonant circuit design of the electronic ballast, causing a compatibility problem.

Further, the driving of an LED uses a DC driving signal, but the driving signal for a fluorescent lamp is a low-frequency, low-voltage AC signal as provided by an AC powerline, a high-frequency, high-voltage AC signal provided by a ballast, or even a DC signal provided by a battery for emergency lighting applications. Since the voltages and frequency spectrums of these types of signals differ significantly, simply performing a rectification to produce the required DC driving signal in an LED tube lamp is not competent at achieving the LED tube lamp's compatibility with traditional driving systems of a fluorescent lamp.

In addition, the LED tube lamp may be provided with power via two ends of the lamp and a user can be easily electrically shocked when one end of the lamp is already inserted into a terminal of a power supply while the other end is held by the user to reach the other terminal of the power supply. For example, when the user is not properly installing or has not properly or completely installed a common LED tube lamp onto a lamp holder or socket, the user may be likely to be electrically shocked by an accidental current through the lamp's internal circuitry and the body of the user touching the lamp or holder. Common or conventional LED tube lamps do not include a device to prevent the accidental electrical shock on the user who is installing the tube lamp.

As a result, currently applied techniques often fall short when attempting to address the above-mentioned worse heat conduction, poor heat dissipation, heat deformation, electric shock, weak electrical connection, smaller driving bandwidth, and variable factor in manufacture defects.

SUMMARY

Therefore, an object of the disclosure is to provide a significantly improved LED tube lamp that dissipates heat more efficiently. A further object of the disclosure is to provide an LED tube lamp that is structurally stronger. Yet another object of the disclosure is to provide an LED tube lamp that minimizes the risk of electric shocks.

According to exemplary embodiments, an LED tube lamp includes a lamp tube, an LED module, a power supply module, a micro switch, and an actuator. The lamp tube has pins for receiving an external driving signal. The LED module is configured for emitting light. The power supply module is configured for supplying power from the external driving signal to the LED module. The micro switch is coupled to the power supply module. And the actuator is configured to cause the micro switch to change to a closed-circuit position to allow the power supply module to supply power to the LED module for emitting light. When the LED tube lamp is properly installed into a lamp holder, the micro switch closes to electrically connect the power supply module to an external driving signal.

According to exemplary embodiments, an LED tube lamp includes a lamp tube, an LED lighting module, a power supply module, a safety switch, and an actuator. The lamp tube has pins for receiving an external driving signal. The LED lighting module is configured for emitting light. The power supply module is configured for supplying power from the external driving signal to the LED lighting module. The safety switch has an input terminal and an output terminal, and includes a thyristor, a current-limiting device, and a micro switch. The input terminal is coupled to one of the first pin and the second pin, and the output terminal is to be coupled to the power supply module.

The thyristor is coupled between the input terminal and the output terminal, and the current-limiting device is coupled between the input terminal and an end of the micro switch, which has another end coupled to a control terminal of the thyristor. And the actuator is for triggering/actuating the micro switch to a closed-circuit position to allow the power supply module to supply power to the LED lighting module for emitting light. When the LED tube lamp is properly installed into a lamp holder, the output terminal of the safety switch is coupled to the power supply module, and the external driving signal is received, the actuator causes the micro switch to change to the closed-circuit position to make the thyristor conduct current, which conducting thyristor allows the power supply module to supply power to the LED lighting module for emitting light.

Various other objects, advantages and features will become readily apparent from the ensuing detailed description, with certain features particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF FIGURES

The following detailed descriptions, given by way of example, and not intended to be limiting solely thereto, will be best be understood in conjunction with the accompanying figures:

FIG. 1 is a cross-sectional view of an LED tube lamp with a light transmissive portion and a reinforcing portion in accordance with an exemplary embodiment;

FIG. 2 is a perspective view illustrating a soldering pad on a bendable circuit sheet of an LED light strip to be joined together with a printed circuit board of a power supply, in accordance with an exemplary embodiment;

FIG. 3 is a planar view illustrating an arrangement of soldering pads on a bendable circuit sheet of an LED light strip in accordance with an exemplary embodiment;

FIG. 4 is a planar view illustrating three soldering pads in a row on a bendable circuit sheet of an LED light strip in accordance with an exemplary embodiment;

FIG. 5 is a planar view illustrating soldering pads arranged in two rows on a bendable circuit sheet of an LED light strip in accordance with an exemplary embodiment;

FIG. 6 is a planar view illustrating four soldering pads arranged in a row on a bendable circuit sheet of an LED light strip in accordance with an exemplary embodiment;

FIG. 7 is a planar view illustrating soldering pads arranged in a two by two matrix on a bendable circuit sheet of an LED light strip in accordance with an exemplary embodiment;

FIG. 8 is a planar view illustrating through holes formed on soldering pads in accordance with an exemplary embodiment;

FIG. 9 is a cross-sectional view illustrating a solder bonding process, which utilizes the soldering pads of the bendable circuit sheet of the LED light strip shown in FIG. 8 taken from side view, and a printed circuit board of a power supply, in accordance with an exemplary embodiment;

FIG. 10 is a cross-sectional view illustrating a solder bonding process, which utilizes the soldering pads of the bendable circuit sheet of the LED light strip shown in FIG. 8, wherein the through hole of the soldering pads is near the edge of the bendable circuit sheet, in accordance with an exemplary embodiment;

FIG. 11 is a planar view illustrating notches formed on soldering pads in accordance with an exemplary embodiment;

FIG. 12 is a cross-sectional view of the LED light strip shown in FIG. 11 along the line A-A, according to some embodiments;

FIG. 13A is a block diagram of an exemplary power supply system for an LED tube lamp according to some embodiments;

FIG. 13B is a block diagram of an exemplary LED lamp according to some embodiments;

FIG. 13C is a block diagram of an exemplary power supply system for an LED tube lamp according to some embodiments;

FIG. 13D is a block diagram of an LED lamp according to some embodiments;

FIG. 14A is a schematic diagram of a rectifying circuit according to some embodiments;

FIG. 14B is a schematic diagram of a rectifying circuit according to some embodiments;

FIG. 14C is a schematic diagram of a rectifying circuit according to some embodiments;

FIG. 14D is a schematic diagram of a rectifying circuit according to some embodiments;

FIG. 15A is a schematic diagram of a terminal adapter circuit according to some embodiments;

FIG. 15B is a schematic diagram of a terminal adapter circuit according to some embodiments;

FIG. 15C is a schematic diagram of a terminal adapter circuit according to some embodiments;

FIG. 15D is a schematic diagram of a terminal adapter circuit according to some embodiments;

FIG. 16A is a block diagram of a filtering circuit according to some embodiments;

FIG. 16B is a schematic diagram of a filtering unit according to some embodiments;

FIG. 16C is a schematic diagram of a filtering unit according to some embodiments;

FIG. 16D is a schematic diagram of a filtering unit according to some embodiments;

FIG. 16E is a schematic diagram of a filtering unit according to some embodiments;

FIG. 17A is a schematic diagram of an LED module according to some embodiments;

FIG. 17B is a schematic diagram of an LED module according to some embodiments;

FIG. 17C is a plan view of a circuit layout of an LED module according to some embodiments;

FIG. 17D is a plan view of a circuit layout of an LED module according to some embodiments;

FIG. 17E is a plan view of a circuit layout of an LED module according to some embodiments;

FIG. 18A is a block diagram of an LED lamp according to some embodiments;

FIG. 18B is a block diagram of a driving circuit according to some embodiments;

FIG. 18C is a schematic diagram of a driving circuit according to some embodiments;

FIG. 18D is a schematic diagram of a driving circuit according to some embodiments;

FIG. 18E is a schematic diagram of a driving circuit according to some embodiments;

FIG. 18F is a schematic diagram of a driving circuit according to some embodiments;

FIG. 18G is a block diagram of a driving circuit according to some embodiments;

FIG. 18H is a graph illustrating a relationship between the voltage Vin and the objective current Tout according to certain embodiments;

FIG. 19A is a block diagram of an exemplary power supply module in an LED tube lamp according to some embodiments;

FIG. 19B is a block diagram of an installation detection module according to some embodiments;

FIG. 19C is a schematic diagram of a detection pulse generating module according to some embodiments;

FIG. 19D is a schematic diagram of a detection determining circuit according to some embodiments;

FIG. 19E is a schematic diagram of a detection result latching circuit according to some embodiments;

FIG. 19F is a schematic diagram of a switch circuit according to some embodiments;

FIG. 20 is a schematic diagram illustrating a structure of an LED tube lamp according to some embodiments; and

FIG. 21 is an alternative micro switch example of FIG. 20, according to some embodiments.

DETAILED DESCRIPTION

The present disclosure now will be described more fully hereinafter with reference to the accompanying drawings, in which various embodiments are shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. These example embodiments are just that—examples—and many implementations and variations are possible that do not require the details provided herein. It should also be emphasized that the disclosure provides details of alternative examples, but such listing of alternatives is not exhaustive. Furthermore, any consistency of detail between various examples should not be interpreted as requiring such detail—it is impracticable to list every possible variation for every feature described herein. The language of the claims should be referenced in determining the requirements of the invention.

In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like numbers refer to like elements throughout. Though the different figures show variations of exemplary embodiments, these figures are not necessarily intended to be mutually exclusive from each other. Rather, as will be seen from the context of the detailed description below, certain features depicted and described in different figures can be combined with other features from other figures to result in various embodiments, when taking the figures and their description as a whole.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items and may be abbreviated as “/”. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Also, the term “exemplary” is intended to refer to an example or illustration.

Although the figures described herein may be referred to using language such as “one embodiment,” or “certain embodiments,” these figures, and their corresponding descriptions are not intended to be mutually exclusive from other figures or descriptions, unless the context so indicates. Therefore, certain aspects from certain figures may be the same as certain features in other figures, and/or certain figures may be different representations or different portions of a particular exemplary embodiment.

It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. Unless the context indicates otherwise, these terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section, for example as a naming convention. Thus, a first element, component, region, layer or section discussed below in one section of the specification could be termed a second element, component, region, layer or section in another section of the specification or in the claims without departing from the teachings of the present invention. In addition, in certain cases, even if a term is not described using “first,” “second,” etc., in the specification, it may still be referred to as “first” or “second” in a claim in order to distinguish different claimed elements from each other.

It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

It will be understood that when an element is referred to as being “connected” or “coupled” to, or “on” another element, it can be directly connected or coupled to, or on the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected,” “directly coupled,” or “directly on” another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). However, the term “contact,” as used herein refers to direct connection (i.e., touching) unless the context indicates otherwise.

Embodiments described herein will be described referring to plan views and/or cross-sectional views by way of ideal schematic views. Accordingly, the exemplary views may be modified depending on manufacturing technologies and/or tolerances. Therefore, the disclosed embodiments are not limited to those shown in the views, but include modifications in configuration formed on the basis of manufacturing processes. Therefore, regions exemplified in figures may have schematic properties, and shapes of regions shown in figures may exemplify specific shapes of regions of elements to which aspects of the invention are not limited.

Although corresponding plan views and/or perspective views of some cross-sectional view(s) may not be shown, the cross-sectional view(s) of device structures illustrated herein provide support for a plurality of device structures that extend along two different directions as would be illustrated in a plan view, and/or in three different directions as would be illustrated in a perspective view. The two different directions may or may not be orthogonal to each other. The three different directions may include a third direction that may be orthogonal to the two different directions. The plurality of device structures may be integrated in a same electronic device. For example, when a device structure (e.g., a solder structure or a pad structure) is illustrated in a cross-sectional view, an electronic device may include a plurality of the device structures (e.g., solder structures or pad structures), as would be illustrated by a plan view of the electronic device. The plurality of device structures may be arranged in an array and/or in a two-dimensional pattern.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

Terms such as “same,” “planar,” or “coplanar,” as used herein when referring to orientation, layout, location, shapes, sizes, amounts, or other measures do not necessarily mean an exactly identical orientation, layout, location, shape, size, amount, or other measure, but are intended to encompass nearly identical orientation, layout, location, shapes, sizes, amounts, or other measures within acceptable variations that may occur, for example, due to manufacturing processes. The term “substantially” may be used herein to emphasize this meaning, unless the context or other statements indicate otherwise. For example, items described as “substantially the same,” “substantially equal,” or “substantially planar,” may be exactly the same, equal, or planar, or may be the same, equal, or planar within acceptable variations that may occur, for example, due to manufacturing processes.

Terms such as “about” or “approximately” may reflect amounts, sizes, orientations, or layouts that vary only in a small relative manner, and/or in a way that does not significantly alter the operation, functionality, or structure of certain elements. For example, a range from “about 0.1 to about 1” may encompass a range such as a 0%-5% deviation around 0.1 and a 0% to 5% deviation around 1, especially if such deviation maintains the same effect as the listed range.

As used herein, items described as being “electrically connected” are configured such that an electrical signal can be passed from one item to the other. Therefore, a passive electrically conductive component (e.g., a wire, pad, internal electrical line, etc.) physically connected to a passive electrically insulative component (e.g., a prepreg layer of a printed circuit board, an electrically insulative adhesive connecting two device, an electrically insulative underfill or mold layer, etc.) is not electrically connected to that component. Moreover, items that are “directly electrically connected,” to each other are electrically connected through one or more passive elements, such as, for example, wires, pads, internal electrical lines, through vias, etc. As such, directly electrically connected components do not include components electrically connected through active elements, such as transistors or diodes. Directly electrically connected elements may be directly physically connected and directly electrically connected.

Components described as thermally connected or in thermal communication are arranged such that heat will follow a path between the components to allow the heat to transfer from the first component to the second component. Simply because two components are part of the same device or package does not make them thermally connected. In general, components which are heat-conductive and directly connected to other heat-conductive or heat-generating components (or connected to those components through intermediate heat-conductive components or in such close proximity as to permit a substantial transfer of heat) will be described as thermally connected to those components, or in thermal communication with those components. On the contrary, two components with heat-insulative materials therebetween, which materials significantly prevent heat transfer between the two components, or only allow for incidental heat transfer, are not described as thermally connected or in thermal communication with each other. The terms “heat-conductive” or “thermally-conductive” do not apply to a particular material simply because it provides incidental heat conduction, but are intended to refer to materials that are typically known as good heat conductors or known to have utility for transferring heat, or components having similar heat conducting properties as those materials.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and/or the present application, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. In addition, unless the context indicates otherwise, steps described in a particular order need not occur in that order.

Referring to FIG. 1, in accordance with an exemplary embodiment, an LED tube lamp comprises a lamp tube 1 and an LED light assembly. The lamp tube 1 includes a light transmissive portion 105 and a reinforcing portion 107. The reinforcing portion 107 is fixedly connected to the light transmissive portion 105.

The LED light assembly is disposed inside the lamp tube 1 and includes an LED light source 202 and an LED light strip 2. The LED light source is thermally and electrically connected to the LED light strip 2, which is in turn thermally connected to the reinforcing portion 107. Though only one LED light source 202 is shown, a plurality of light sources 202 may be arranged on the LED light strip 2. For example, light sources 202 may be arranged in one or more rows extending along a length direction of the LED light strip 2, which may extend along a length direction of the lamp tube 1. Heat generated by the LED light source 202 is first transmitted to the LED light strip 2 and then to the reinforcing portion 107 before egressing the lamp tube 1. Thermal connection is achieved with thermally conductive tapes or conventional mechanical fasteners such as screws aided by thermal grease to eliminate air gaps from interface areas. In certain embodiments, the LED light strip 2 may be formed from a bendable circuit sheet, for example that may be flexible. As described further below, the bendable circuit sheet, also described as a bendable circuit board, may be disposed on the lamp tube 1 to be bent away from the lamp tube 1, for example at longitudinal ends of the bendable circuit sheet.

Typically, the lamp tube 1 has a shape of an elongated cylinder, which is a straight structure. However, the lamp tube 1 can take any curved structure such as a ring or a horseshoe. The cross section of the lamp tube 1 is typically a circle, but may also be other shapes, such as an ellipse or a polygon. Alternatively, the cross section of the lamp tube 1 may have an irregular shape depending on the shapes of, respectively, the light transmissive portion 105 and the reinforcing portion 107 and on the manner the two portions interconnect to form the lamp tube 1.

The lamp tube 1 is a glass tube, a plastic tube or a tube made of any other suitable material or combination of materials. In some embodiments, a plastic lamp tube is made from light transmissive plastic, thermally conductive plastic or a combination of both. For example, the light transmissive plastic may be one of translucent polymer matrices such as polymethyl methacrylate, polycarbonate, polystyrene, poly(styrene-co-methyl methacrylate) and a mixture thereof. In some embodiments, the strength and elasticity of thermally conductive plastic is enhanced by bonding a plastic matrix with glass fibers. In an embodiment, an outer shell of lamp tube includes a plurality of layers made from distinct materials. For example, the lamp tube may include a plastic tube coaxially sheathed by a glass tube.

In one embodiment, the light transmissive portion 105 is made from light transmissive plastic, and the reinforcing portion is 107 made from thermally conductive plastic. Injection molding may be used for producing the light transmissive portion 105 in a first piece and for producing the reinforcing portion 107 in a separate second piece. The first piece and the second piece may be configured to be clipped together, buckled together, glued together or otherwise fixedly interconnected to form the lamp tube 1. Alternatively, injection molding may be used for producing the entire lamp tube 1, which includes the light transmissive portion 105 and the reinforcing portion 107, in an integral piece of the lamp tube 1, by feeding two types of plastic materials into a molding process. In an alternative embodiment, the reinforcing portion is made of metal having good thermal conductivity such as aluminum alloy and copper alloy.

Respective shapes of the light transmissive portion 105 and the reinforcing portion 107, how the two portions 105, 107 interconnect to form the lamp tube 1 and, particularly, the respective proportions of the two portions 105, 107 in the lamp tube depend on a desired totality of considerations such as field angle, heat dissipation efficiency and structural strength. A wider field angle—potentially at the expense of heat dissipation capability and structural strength—is achieved when the proportion of the light transmissive portion increases 105 in relation to that of the reinforcing portion 107. By contrast, the lamp tube benefits from an increased proportion of the reinforcing portion 107 in relation to that of the light transmissive portion in such ways as better heat dissipation and rigidity but potentially loses field angle.

In some embodiments, the reinforcing portion 107 includes a plurality of protruding parts. In other embodiments, a plurality of protruding parts are disposed on the surface of the LED light strip 2 that is not covered by the LED light assembly. Like fins on a heatsink, each protruding part boosts heat dissipation by increasing the surface area of the reinforcing portion 107 and the LED light strip 2. The protruding parts are disposed equidistantly, or alternatively, not equidistantly.

Referring to FIG. 1, the lamp tube 1 depicted in FIG. 1 has a shape of a circular cylinder. For example, a cross section of the lamp tube 1 defines a circle. A line H-H cuts the circle horizontally into two equal halves along a diameter of the circle. A cross section of the light transmissive portion 105 defines an upper segment on the circle. A cross section of the reinforcing portion 107 defines a lower segment on the circle. A dividing line 104 parallel to the line H-H is shared by the two segments. In the embodiment, the dividing line 104 sits exactly on the line H-H. Consequently, the area of the upper segment is the same as that of the lower segment. In one embodiment, the cross section of the light transmissive portion 105 has a same area as that of the reinforcing portion 107.

In an alternative embodiment, the dividing line 104 is spaced apart from the line H-H. For example, when the dividing line 104 is below the line H-H, the upper segment, which encompasses the light transmissive portion, has a greater area than the lower segment, which encompasses the reinforcing portion. The lamp tube, which includes an enlarged light transmissive portion, is thus configured to achieve a field angle wider than 180 degrees; however, other things equal, the lamp tube surrenders some heat dissipation capability, structural strength or both due to a diminished reinforcing portion 107. By contrast, the lamp tube 1 may have an enlarged reinforcing portion 107 and a diminished light transmissive portion 105 if the dividing line rises above the line H-H. Other things equal, the lamp tube 1, now having an enlarged reinforcing portion 107, is configured to exhibit higher heat dissipation capability, structural strength or both; however, the field angle of the lamp tube 1 will dwindle due to diminished dimensions of the light transmissive portion 105. In either case, the dividing line 104 may be parallel to the line H-H, or where the areas of the upper segment and lower segment are not equal, in some embodiments, rather than being parallel, the dividing line 104 may have another orientation. For example, each dividing line 104 may extend in a direction that extends radially from a center of the lamp tube 1, as viewed from a cross-section.

According to certain embodiments, the LED tube lamp is configured to convert bright spots coming from the LED light source into an evenly distributed luminous output. In one embodiment, a light diffusion layer is disposed on an inner surface of the lamp tube 1 or an outer surface of the lamp tube 1. In another embodiment, a diffusion laminate is disposed over the LED light source 202. In yet another embodiment, the lamp tube 1 has a glossy outer surface and a frosted inner surface. The inner surface is rougher than the outer surface. The roughness R_(a) of the inner surface may be, for example, from 0.1 to 40 μm. In some embodiments, roughness R_(a) of the inner surface may be from 1 to 20 μm. Controlled roughness of the surface is obtained mechanically, for example, by a cutter grinding against a workpiece, deformation on a surface of a workpiece being cut off or high frequency vibration in the manufacturing system. Alternatively, roughness is obtained chemically, for example, by etching a surface. Depending on the luminous effect the lamp tube 1 is designed to produce, a suitable combination of amplitude and frequency of a roughened surface is provided by a matching combination of workpiece and finishing technique. Also, various of the diffusion mechanisms described herein can be combined in various ways to obtain a desired effect.

In alternative embodiments, the diffusion layer is in the form of an optical diffusion coating, which is composed of any one of calcium carbonate, halogen calcium phosphate and aluminum oxide, or any combination thereof. When the optical diffusion coating is made from a calcium carbonate with suitable solution, an excellent light diffusion effect and transmittance to exceed 90% can be obtained.

In the embodiment, the composition of the diffusion layer in form of the optical diffusion coating includes calcium carbonate, strontium phosphate (e.g., CMS-5000, white powder), thickener, and a ceramic activated carbon (e.g., ceramic activated carbon SW-C, which is a colorless liquid). Specifically, in some embodiments, such an optical diffusion coating on the inner circumferential surface of the glass tube has an average thickness ranging between about 20 to about 30 μm. For example, the thickness, which may be a uniform thickness, may be 20 μm, 30 μm, or may have a value therebetween. A light transmittance of the diffusion layer using this optical diffusion coating is about 90%. Generally speaking, the light transmittance of the diffusion layer ranges from 85% to 96%. For example, the light transmittance of the diffusion layer may be 85%, 96%, or have a value therebetween. In addition, this diffusion layer can also provide electrical isolation for reducing risk of electric shock to a user upon breakage of the lamp tube 1. Furthermore, the diffusion layer provides an improved illumination distribution uniformity of the light outputted by the LED light sources 202 such that the light can illuminate the back of the light sources 202 and the side edges of the bendable circuit sheet so as to avoid the formation of dark regions inside the lamp tube 1 and improve the illumination comfort. In another possible embodiment, the light transmittance of the diffusion layer can be reduced to be about 92% to 94% while the thickness of the diffusion layer ranges from about 200 to about 300 μm.

In another embodiment, the optical diffusion coating can also be made of a mixture including a calcium carbonate-based substance, some reflective substances like strontium phosphate or barium sulfate, a thickening agent, ceramic activated carbon, and deionized water. The mixture is coated on the inner circumferential surface of the glass tube and has an average thickness ranging between about 20 to about 30 μm. In view of the diffusion phenomena in microscopic terms, light is reflected by particles. The particle size of the reflective substance such as strontium phosphate or barium sulfate will be much larger than the particle size of the calcium carbonate. Therefore, adding a small amount of reflective substance in the optical diffusion coating can effectively increase the diffusion effect of light.

In other embodiments, halogen calcium phosphate or aluminum oxide can also serve as the main material for forming the diffusion layer. The particle size of the calcium carbonate is about 2 to 4 while the particle size of the halogen calcium phosphate and aluminum oxide are about 4 to 6 μm and 1 to 2 μm, respectively. When the light transmittance is required to be 85% to 92%, the average thickness for the optical diffusion coating mainly having the calcium carbonate may be about 20 to about 30 while the average thickness for the optical diffusion coating mainly having the halogen calcium phosphate may be about 25 to about 35 and the average thickness for the optical diffusion coating mainly having the aluminum oxide may be about 10 to about 15 However, when the required light transmittance is up to 92% and even higher, the optical diffusion coating mainly having the calcium carbonate, the halogen calcium phosphate, or the aluminum oxide can be made thinner.

The main material and the corresponding thickness of the optical diffusion coating can be decided according to the place for which the lamp tube 1 is used and the light transmittance required. In some embodiments, the higher the desired light transmittance of the diffusion layer, the more apparent the grainy visual appearance of the light sources is.

In one embodiment, the LED tube lamp is configured to reduce internal reflectance by applying a layer of anti-reflection coating to an inner surface of the lamp tube 1. The coating has an upper boundary, which divides the inner surface of the lamp tube and the anti-reflection coating, and a lower boundary, which divides the anti-reflection coating and the air in the lamp tube 1. Light waves reflected by the upper and lower boundaries of the coating interfere with one another to reduce reflectance. In certain embodiments, the coating is made from a material with a refractive index of a square root of the refractive index of the light transmissive portion 105 of the lamp tube 1 by vacuum deposition. Tolerance of the coating's refractive index is ±20%. The thickness of the coating is chosen to produce destructive interference in the light reflected from the interfaces and constructive interference in the corresponding transmitted light. In an additional embodiment, reflectance is further reduced by using alternating layers of a low-index coating and a higher-index coating. The multi-layer structure is designed to, when setting parameters such as combination and permutation of layers, thickness of a layer, refractive index of the material, give low reflectivity over a broad band that covers at least 60%, or in some embodiments, 80% of the wavelength range beaming from the LED light source 202. In some embodiments, three successive layers of anti-reflection coatings are applied to an inner surface of the lamp tube 1 to obtain low reflectivity over a wide range of frequencies. The thicknesses of the coatings are chosen to give the coatings optical depths of, respectively, one half, one quarter and one half of the wavelength range coming from the LED light source 202. Dimensional tolerance for the thickness of the coating is set at ±20%.

In some embodiments, any type of power supply can be electrically connected to the LED light strip 2 by means of a traditional wire bonding technique, in which a metal wire has an end connected to the power supply and has the other end connected to the LED light strip 2. Furthermore, the metal wire may be wrapped with an electrically insulating tube to protect a user from being electrically shocked. However, the bonded wires tend to be easily broken during transportation and can therefore cause quality issues.

In still another embodiment, the connection between the power supply 5 and the LED light strip 2 may be accomplished via soldering (e.g., using tin), rivet bonding, or welding. One way to secure the LED light strip 2 is to provide the adhesive sheet at one side thereof and adhere the LED light strip 2 to the inner surface of the lamp tube 1 via the adhesive sheet. Two ends of the LED light strip 2 can be either fixed to or detached from the inner surface of the lamp tube 1.

In case where two ends of the LED light strip 2 are fixed to the inner surface of the lamp tube 1, a bendable circuit sheet of the LED light strip 2 may be provided with a female plug, and a power supply, for example at ends of the bendable circuit sheet, is provided with the male plug to accomplish the connection between the LED light strip 2 and the power supply. In this case, the male plug of the power supply is inserted into the female plug to establish electrical connection.

In a case where two ends of the LED light strip 2 are detached from the inner surface of the lamp tube (e.g., if an adhesive wears out) and that the LED light strip 2 is connected to the power supply via wire-bonding, any movement in subsequent transportation is likely to cause the bonded wires to break. Therefore, in some embodiments, the connection between the light strip 2 and a power supply at ends of the light strip 2 could be accomplished via direct soldering. For example, the ends of the LED light strip 2 including a bendable circuit sheet can be arranged to pass over a strengthened transition region of a lamp tube, and be directly solder bonded to an output terminal of a power supply such that the product quality is improved without using wires. In this way, the female plug and the male plug respectively provided for the LED light strip 2 and the power supply are no longer needed. As discussed herein, a transition region of the lamp tube refers to regions outside a central portion of the lamp tube and inside terminal ends of the lamp tube. For example, a central portion of the lamp tube may have a constant diameter, and each transition region between the central portion and a terminal end of the lamp tube may have a changing diameter (e.g., at least part of the transition region may become more narrow moving in a direction from the central portion to the terminal end of the lamp tube). End caps including the power supply may be disposed at the terminal ends of the lamp tube, and may cover part of the transition region. In some embodiments, the ends of the bendable circuit sheet may be connected to a power supply in an end cap of the LED tube lamp. For example, the ends may be connected in a manner such that a portion of the bendable circuit sheet is bent away from the lamp tube and passes through the transition region where a lamp tube narrows, and such that the bendable circuit sheet vertically overlaps part of a power supply within an end cap of the LED tube lamp.

Referring to FIG. 2, a power supply 5 described herein may include various elements for providing power to the LED light strip 2. For example, it may include power converters or other circuit elements for providing power to the LED light strip 2. In some embodiments, power supply 5 may include a printed circuit board. An output terminal of the printed circuit board of the power supply 5 may have soldering pads “a” provided with an amount of solder (e.g., tin solder) with a thickness sufficient to later form a solder joint. Correspondingly, the ends of the LED light strip 2 may have soldering pads “b”. The soldering pads “a” on the output terminal of the printed circuit board of the power supply 5 are soldered to the soldering pads “b” on the LED light strip 2 via the solder on the soldering pads “a”. The soldering pads “a” and the soldering pads “b” may be face to face during soldering such that the connection between the LED light strip 2 and the printed circuit board of the power supply 5 is the most firm. However, this kind of soldering may involve a thermo-compression head pressing on the rear surface of the LED light strip 2 and heating the solder, e.g., the LED light strip 2 intervenes between the thermo-compression head and the solder. This may cause reliability problems. Referring to FIG. 8, a through hole may be formed in each of the soldering pads “b” on the LED light strip 2 to allow the soldering pads “b” to overlay the soldering pads “b” without being face-to-face. In this case, the thermo-compression head directly presses solder on the soldering pads “a” on surface of the printed circuit board of the power supply 5 when the soldering pads “a” and the soldering pads “b” are vertically aligned.

Referring again to FIG. 2, two ends of the LED light strip 2 detached from the inner surface of the lamp tube 1 are formed as freely extending portions 21, while most of the LED light strip 2 is attached and secured to the inner surface of the lamp tube 1. One of the freely extending portions 21 has the soldering pads “b” as mentioned above. Upon assembling of the LED tube lamp, the freely extending end portions 21 along with the soldered connection of the printed circuit board of the power supply 5 and the LED light strip 2 would be coiled, curled up or deformed to be fittingly accommodated inside the lamp tube 1. The freely extending portions 21 may be different from a fixed portion of the LED light strip 2 attached to the lamp tube 1, in that the fixed portion may conform to the shape of the inner surface of the lamp tube 1 and may be fixed thereto, while the freely extending portion 21 may have a shape that does not conform to the shape of the lamp tube 1. As shown in FIG. 2, the freely extending portion 21 may be bent away from the lamp tube 1. For example, there may be a space between an inner surface of the lamp tube 1 and the freely extending portion 21.

In one embodiment, during the connection of the LED light strip 2 and the power supply 5, the soldering pads “b” and the soldering pads “a” and the LED light sources 202 are on surfaces facing toward the same direction and the soldering pads “b” on the LED light strip 2 are each formed with a through hole “e” as shown in FIG. 8 such that the soldering pads “b” and the soldering pads “a” communicate with each other via the through holes “e”. When the freely extending end portions 21 are deformed due to contraction or curling up, the soldered connection of the printed circuit board of the power supply 5 and the LED light strip 2 exerts a lateral tension on the power supply 5. Furthermore, the soldered connection of the printed circuit board of the power supply 5 and the LED light strip 2 also exerts a downward tension on the power supply 5 when compared with the situation where the soldering pads “a” of the power supply 5 and the soldering pads “b” of the LED light strip 2 are face to face. This downward tension on the power supply 5 comes from the solders (e.g., tin solders) inside the through holes “e” and forms a stronger and more secure electrical connection between the LED light strip 2 and the power supply 5.

Referring to FIG. 3, in one embodiment, the soldering pads “b” of the LED light strip 2 are two separate pads to electrically connect the positive and negative electrodes of the bendable circuit sheet of the LED light strip 2, respectively. The size of the soldering pads “b” may be, for example, about 3.5×2 mm². The printed circuit board of the power supply 5 is correspondingly provided with soldering pads “a” having reserved tin solders (or solders formed from other suitable metal) and the height of the tin solders suitable for subsequent automatic solder bonding process may be generally, for example, about 0.1 to 0.7 mm, in some embodiments 0.3 to 0.5 mm. In some exemplary embodiments, the height of the tin solders suitable for a subsequent automatic solder bonding process may be about 0.4 mm. An electrically insulating through hole “c” may be formed between the two soldering pads “b” to isolate and prevent the two soldering pads from electrically shorting during soldering. Furthermore, an extra positioning opening “d” may also be provided behind the electrically insulating through hole “c” to allow an automatic soldering machine to quickly recognize the position of the soldering pads “b”.

There is at least one soldering pad “b” for separately connecting to the positive and negative electrodes of the LED light sources 202. For the sake of achieving scalability and compatibility, the amount of the soldering pads “b” on each end of the LED light strip 2 may be more than one such as two, three, four, or more than four. When there is only one soldering pad “b” provided at each end of the LED light strip 2, the two ends of the LED light strip 2 are electrically connected to the power supply 5 to form a loop, and various electrical components can be used. For example, a capacitance may be replaced by an inductance to perform current regulation. Referring to FIGS. 4 to 7, when each end of the LED light strip 2 has three soldering pads, the third soldering pad can be grounded; when each end of the LED light strip 2 has four soldering pads, the fourth soldering pad can be used as a signal input terminal. Correspondingly, in various embodiments, the power supply 5 should have same amount of soldering pads “a” as that of the soldering pads “b” on the LED light strip 2. As long as electrical short between the soldering pads “b” can be prevented, the soldering pads “b” can be arranged according to the dimension of the actual area for disposition, for example, three soldering pads can be arranged in a row or two rows. In other embodiments, the amount of the soldering pads “b” on the bendable circuit sheet of the LED light strip 2 may be reduced by rearranging the circuits on the bendable circuit sheet of the LED light strip 2. The lesser the amount of the soldering pads, the easier the fabrication process becomes. On the other hand, a greater number of soldering pads may improve and secure the electrical connection between the LED light strip 2 and the output terminal of the power supply 5.

Referring to FIG. 8, as discussed previously, in another embodiment, each soldering pads “b” is formed with a through hole “e” having a diameter generally of about 1 to 2 mm, in some embodiments of about 1.2 to 1.8 mm, and in yet some embodiments of about 1.5 mm. The through hole “e” connects the soldering pad “a” with the soldering pad “b” so that the solder on the soldering pads “a” passes through the through holes “e” and finally reaches the soldering pads “b”. A smaller through hole would make it difficult for the solder to pass. The solder accumulates around the through holes “e” upon exiting the through holes “e” and condenses to form a solder ball “g” with a larger diameter than that of the through holes “e” upon condensing. Such a solder ball “g” functions as a rivet to further increase the stability of the electrical connection between the soldering pads “a” on the power supply 5 and the soldering pads “b” on the LED light strip 2.

Referring to FIGS. 9 to 10, in other embodiments, when a distance from the through hole “e” to the side edge of the LED light strip 2 is less than 1 mm, the tin solder may pass through the through hole “e” to accumulate on the periphery of the through hole “e”, and extra tin solder may spill over the soldering pads “b” to reflow along the side edge of the LED light strip 2 and join the tin solder on the soldering pads “a” of the power supply 5. The tin solder then condenses to form a structure like a rivet to firmly secure the LED light strip 2 onto the printed circuit board of the power supply 5 such that reliable electric connection is achieved. Referring to FIG. 11 and FIG. 12, in another embodiment, the through hole “e” can be replaced by a notch “f” formed at the side edge of the soldering pads “b” for the tin solder to easily pass through the notch “f” and accumulate on the periphery of the notch “f” and to form a solder ball with a larger diameter than that of the notch “e” upon condensing. Such a solder ball may be formed like a C-shape rivet to enhance the secure capability of the electrically connecting structure.

The abovementioned through hole “e” or notch “f” might be formed in advance of soldering or formed by direct punching with a thermo-compression head during soldering. The portion of the thermo-compression head for touching the tin solder may be flat, concave, or convex, or any combination thereof. The portion of the thermo-compression head for restraining the object to be soldered such as the LED light strip 2 may be strip-like or grid-like. In some embodiments, the portion of the thermo-compression head for touching the tin solder does not completely cover the through hole “e” or the notch “f,” to make sure that the tin solder is able to pass through the through hole “e” or the notch “f”. The portion of the thermo-compression head being concave may function as a compartment to receive the solder ball.

The power supply 5 is electrically coupled to the LED light strip 2 and various features and applications of the related power supply assembly are described below. The example circuits and the assemblies mentioned below may be all disposed on the reinforcing portion in the lamp tube to increase the heat dissipating area and efficiency, simplify the circuit design in the end cap, and provide an easier control for the length of the lamp tube in manufacturing. However, in some embodiments, some of example circuits and assemblies described below are kept in the end cap (e.g. resistors, or capacitors, or the components with smaller volume or smaller power consumption, the components generating less heat or having better heat resistance) and the others are disposed on the reinforcing portion (e.g. chips, inductors, transistors, or the components with bigger volume, the components generating much heat or having poor heat resistance) so as to increase the heat dissipating area and efficiency and simplify the circuit design in the end cap. The implementations are not limited to the disclosed embodiments.

In some embodiments, for example, the circuits and the assemblies disposed on the reinforcing portion in the lamp tube may be implemented by surface mount components. Some of the circuits and the assemblies may be disposed on the LED light strip and then be electrically connected to the circuit(s) kept in the end cap via a male-female plug or a wire with an insulating coating/layer for achieving the isolation effect. Or, the circuits and the assemblies related to the power supply may all be disposed on the LED light strip to reduce the reserved length of the LED light strip, which is used for connecting to other circuit board(s), and also to reduce the allowable error length and omit the process for electrically connecting two or more circuit boards (e.g., the bendable circuit board and a circuit board of a power supply), so that the lengths of the lamp tube and the LED light strip could be controlled more precisely. The circuits and the assemblies and the LEDs may be disposed on the same or different side of the reinforcing portion. In some embodiments, the circuits and the assemblies and the LEDs may be disposed on the same side to reduce the process of making through hole(s) on the reinforcing portion for electrically connection. The implementations are not limited to the disclosed embodiments.

Next, examples of the circuit design and of a power supply system and module are described as follows.

FIG. 13A is a block diagram of a power supply system for an LED tube lamp according to an embodiment. Referring to FIG. 13A, an AC power supply 508 is used to supply an AC supply signal, and may be an AC powerline with a voltage rating, for example, in 100-277 volts and a frequency rating, for example, of 50 or 60 Hz. A lamp driving circuit 505 receives and then converts the AC supply signal into an AC driving signal as an external driving signal. In some embodiments, the power supply 508 and the lamp driving circuit 505 are outside of the LED tube lamp. For example, the lamp driving circuit 505 may be part of a lamp socket or lamp holder into which the LED tube lamp is inserted. Lamp driving circuit 505 may be for example an electronic ballast used to convert the AC powerline into a high-frequency high-voltage AC driving signal. Common types of electronic ballast include instant-start ballast, program-start or rapid-start ballast, etc., which may all be applicable to the LED tube lamp. The voltage of the AC driving signal is likely higher than 300 volts, and is in some embodiments in the range of about 400-700 volts. The frequency of the AC driving signal may be higher than 10 k Hz. In some embodiments, the frequency of the AC driving signal may be in the range of about 20 k-50 k Hz. The LED tube lamp 500 receives an external driving signal and is thus driven to emit light. In one embodiment, the external driving signal comprises the AC driving signal from lamp driving circuit 505. In one embodiment, LED tube lamp 500 is in a driving environment in which it is power-supplied at its one end cap having two conductive pins 501 and 502, which are coupled to lamp driving circuit 505 to receive the AC driving signal. The two conductive pins 501 and 502 may be electrically connected to, either directly or indirectly, the lamp driving circuit 505.

It is worth noting that lamp driving circuit 505 may be omitted and is therefore depicted by a dotted line. In one embodiment, if lamp driving circuit 505 is omitted, AC power supply 508 is directly connected to pins 501 and 502, which then receive the AC supply signal as an external driving signal.

In addition to the above use with a single-end power supply, LED tube lamp 500 may instead be used with a dual-end power supply to one pin at each of the two ends of an LED lamp tube.

FIG. 13B is a block diagram of an LED lamp according to one embodiment. Referring to FIG. 13B, a power supply module of the LED lamp includes a rectifying circuit 510 and a filtering circuit 520, and may also include some components of an LED lighting module 530. Rectifying circuit 510 is coupled to pins 501 and 502 to receive and then rectify an external driving signal, so as to output a rectified signal at output terminals 511 and 512. The external driving signal may be the AC driving signal or the AC supply signal described with reference to FIG. 13A, or may even be a DC signal, which embodiments do not alter the LED lamp. Filtering circuit 520 is coupled to the first rectifying circuit for filtering the rectified signal to produce a filtered signal. For instance, filtering circuit 520 is coupled to terminals 511 and 512 to receive and then filter the rectified signal, so as to output a filtered signal at output terminals 521 and 522. LED lighting module 530 is coupled to filtering circuit 520, to receive the filtered signal for emitting light. For instance, LED lighting module 530 may be a circuit coupled to terminals 521 and 522 to receive the filtered signal and thereby to drive an LED unit (not shown) in LED lighting module 530 to emit light. Details of these operations are described in below descriptions of certain embodiments.

Although two output terminals 511 and 512 and two output terminals 521 and 522 are depicted in embodiments of these Figs., in practice the number of ports or terminals for coupling between rectifying circuit 510, filtering circuit 520, and LED lighting module 530 may be one or more depending on the signal transmission between the circuits or devices.

In addition, the power supply module of the LED lamp described in FIG. 13B, and embodiments of the power supply module of an LED lamp described below, may each be used in the LED tube lamp 500 in FIG. 13A, and may also be used in any other type of LED lighting structure having two conductive pins used to conduct power, such as LED light bulbs, personal area lights (PAL), plug-in LED lamps with different types of bases (such as types of PL-S, PL-D, PL-T, PL-L, etc.), etc.

FIG. 13C is a block diagram of a power supply system for an LED tube lamp according to an embodiment. Referring to FIG. 13C, an AC power supply 508 is used to supply an AC supply signal. A lamp driving circuit 505 receives and then converts the AC supply signal into an AC driving signal. An LED tube lamp 500 receives an AC driving signal from lamp driving circuit 505 and is thus driven to emit light. In this embodiment, LED tube lamp 500 is power-supplied at its both end caps respectively having two pins 501 and 502 and two pins 503 and 504, which are coupled to lamp driving circuit 505 to concurrently receive the AC driving signal to drive an LED unit (not shown) in LED tube lamp 500 to emit light. AC power supply 508 may be e.g. the AC powerline, and lamp driving circuit 505 may be a stabilizer or an electronic ballast.

FIG. 13D is a block diagram of an LED lamp according to an embodiment. Referring to FIG. 13D, a power supply module of an LED lamp includes a rectifying circuit 510, a filtering circuit 520, and a rectifying circuit 540, and may also include some components of an LED lighting module 530. Rectifying circuit 510 is coupled to pins 501 and 502 to receive and then rectify an external driving signal conducted by pins 501 and 502. Rectifying circuit 540 is coupled to pins 503 and 504 to receive and then rectify an external driving signal conducted by pins 503 and 504. Therefore, the power supply module of the LED lamp may include two rectifying circuits 510 and 540 configured to output a rectified signal at output terminals 511 and 512. Filtering circuit 520 is coupled to terminals 511 and 512 to receive and then filter the rectified signal, so as to output a filtered signal at output terminals 521 and 522. LED lighting module 530 is coupled to terminals 521 and 522 to receive the filtered signal and thereby to drive an LED unit (not shown) in LED lighting module 530 to emit light

The power supply module of the LED lamp in this embodiment of FIG. 13D may be used in LED tube lamp 500 with a dual-end power supply in FIG. 13C. It is worth noting that since the power supply module of the LED lamp comprises rectifying circuits 510 and 540, the power supply module of the LED lamp may be used in LED tube lamp 500 with a single-end power supply in FIG. 13A, to receive an external driving signal (such as the AC supply signal or the AC driving signal described above). The power supply module of an LED lamp in this embodiment and other embodiments herein may also be used with a DC driving signal.

FIG. 14A is a schematic diagram of a rectifying circuit according to an embodiment. Referring to FIG. 14A, rectifying circuit 610 includes rectifying diodes 611, 612, 613, and 614, configured to full-wave rectify a received signal. Diode 611 has an anode connected to output terminal 512, and a cathode connected to pin 502. Diode 612 has an anode connected to output terminal 512, and a cathode connected to pin 501. Diode 613 has an anode connected to pin 502, and a cathode connected to output terminal 511. Diode 614 has an anode connected to pin 501, and a cathode connected to output terminal 511.

When pins 501 and 502 receive an AC signal, rectifying circuit 610 operates as follows. During the connected AC signal's positive half cycle, the AC signal is input through pin 501, diode 614, and output terminal 511 in sequence, and later output through output terminal 512, diode 611, and pin 502 in sequence. During the connected AC signal's negative half cycle, the AC signal is input through pin 502, diode 613, and output terminal 511 in sequence, and later output through output terminal 512, diode 612, and pin 501 in sequence. Therefore, during the connected AC signal's full cycle, the positive pole of the rectified signal produced by rectifying circuit 610 remains at output terminal 511, and the negative pole of the rectified signal remains at output terminal 512. Accordingly, the rectified signal produced or output by rectifying circuit 610 is a full-wave rectified signal.

When pins 501 and 502 are coupled to a DC power supply to receive a DC signal, rectifying circuit 610 operates as follows. When pin 501 is coupled to the anode of the DC supply and pin 502 to the cathode of the DC supply, the DC signal is input through pin 501, diode 614, and output terminal 511 in sequence, and later output through output terminal 512, diode 611, and pin 502 in sequence. When pin 501 is coupled to the cathode of the DC supply and pin 502 to the anode of the DC supply, the DC signal is input through pin 502, diode 613, and output terminal 511 in sequence, and later output through output terminal 512, diode 612, and pin 501 in sequence. Therefore, no matter what the electrical polarity of the DC signal is between pins 501 and 502, the positive pole of the rectified signal produced by rectifying circuit 610 remains at output terminal 511, and the negative pole of the rectified signal remains at output terminal 512.

Therefore, rectifying circuit 610 in this embodiment can output or produce a proper rectified signal regardless of whether the received input signal is an AC or DC signal.

FIG. 14B is a schematic diagram of a rectifying circuit according to an embodiment. Referring to FIG. 14B, rectifying circuit 710 includes rectifying diodes 711 and 712, configured to half-wave rectify a received signal. Diode 711 has an anode connected to pin 502, and a cathode connected to output terminal 511. Diode 712 has an anode connected to output terminal 511, and a cathode connected to pin 501. Output terminal 512 may be omitted or grounded depending on actual applications.

Next, exemplary operation(s) of rectifying circuit 710 is described as follows.

In one embodiment, during a received AC signal's positive half cycle, the electrical potential at pin 501 is higher than that at pin 502, so diodes 711 and 712 are both in a cutoff state as being reverse-biased, making rectifying circuit 710 not outputting a rectified signal. During a received AC signal's negative half cycle, the electrical potential at pin 501 is lower than that at pin 502, so diodes 711 and 712 are both in a conducting state as being forward-biased, allowing the AC signal to be input through diode 711 and output terminal 511, and later output through output terminal 512, a ground terminal, or another end of the LED tube lamp not directly connected to rectifying circuit 710. Accordingly, the rectified signal produced or output by rectifying circuit 710 is a half-wave rectified signal.

FIG. 14C is a schematic diagram of a rectifying circuit according to an embodiment. Referring to FIG. 14C, rectifying circuit 810 includes a rectifying unit 815 and a terminal adapter circuit 541. In this embodiment, rectifying unit 815 comprises a half-wave rectifier circuit including diodes 811 and 812 and configured to half-wave rectify. Diode 811 has an anode connected to an output terminal 512, and a cathode connected to a half-wave node 819. Diode 812 has an anode connected to half-wave node 819, and a cathode connected to an output terminal 511. Terminal adapter circuit 541 is coupled to half-wave node 819 and pins 501 and 502, to transmit a signal received at pin 501 and/or pin 502 to half-wave node 819. By means of the terminal adapting function of terminal adapter circuit 541, rectifying circuit 810 allows connection of two input terminals (connected to pins 501 and 502) and two output terminals 511 and 512.

In certain embodiments, rectifying circuit 810 operates as follows.

During a received AC signal's positive half cycle, the AC signal may be input through pin 501 or 502, terminal adapter circuit 541, half-wave node 819, diode 812, and output terminal 511 in sequence, and later output through another end or circuit of the LED tube lamp. During a received AC signal's negative half cycle, the AC signal may be input through another end or circuit of the LED tube lamp, and later output through output terminal 512, diode 811, half-wave node 819, terminal adapter circuit 541, and pin 501 or 502 in sequence.

It's worth noting that terminal adapter circuit 541 may comprise a resistor, a capacitor, an inductor, or any combination thereof, for performing functions of voltage/current regulation or limiting, types of protection, current/voltage regulation, etc. Descriptions of these functions are presented below.

In practice, rectifying unit 815 and terminal adapter circuit 541 may be interchanged in position (as shown in FIG. 14D), without altering the function of half-wave rectification. FIG. 14D is a schematic diagram of a rectifying circuit according to an embodiment. Referring to FIG. 14D, diode 811 has an anode connected to pin 502 and diode 812 has a cathode connected to pin 501. A cathode of diode 811 and an anode of diode 812 are connected to half-wave node 819. Terminal adapter circuit 541 is coupled to half-wave node 819 and output terminals 511 and 512. During a received AC signal's positive half cycle, the AC signal may be input through another end or circuit of the LED tube lamp, and later output through output terminal 512 or 512, terminal adapter circuit 541, half-wave node 819, diode 812, and pin 501 in sequence. During a received AC signal's negative half cycle, the AC signal may be input through pin 502, diode 811, half-wave node 819, terminal adapter circuit 541, and output node 511 or 512 in sequence, and later output through another end or circuit of the LED tube lamp.

Terminal adapter circuit 541 in embodiments shown in FIGS. 14C and 14D may be omitted and is therefore depicted by a dotted line. If terminal adapter circuit 541 of FIG. 14C is omitted, pins 501 and 502 will be coupled to half-wave node 819. If terminal adapter circuit 541 of FIG. 14D is omitted, output terminals 511 and 512 will be coupled to half-wave node 819.

Rectifying circuit 510 as shown and explained in FIGS. 14A-D can constitute or be the rectifying circuit 540 shown in FIG. 13D, as having pins 503 and 504 for conducting instead of pins 501 and 502.

Next, an explanation follows as to choosing embodiments and their combinations of rectifying circuits 510 and 540, with reference to FIGS. 13B and 13D.

Rectifying circuit 510 in embodiments shown in FIG. 13B may comprise the rectifying circuit 610 in FIG. 14A.

Rectifying circuits 510 and 540 in embodiments shown in FIG. 13D may each comprise any one of the rectifying circuits in FIGS. 14A-D, and terminal adapter circuit 541 in FIGS. 14C-D may be omitted without altering the rectification function used in an LED tube lamp. When rectifying circuits 510 and 540 each comprise a half-wave rectifier circuit described in FIGS. 14B-D, during a received AC signal's positive or negative half cycle, the AC signal may be input from one of rectifying circuits 510 and 540, and later output from the other rectifying circuit 510 or 540. Further, when rectifying circuits 510 and 540 each comprise the rectifying circuit described in FIG. 14C or 14D, or when they comprise the rectifying circuits in FIGS. 14C and 14D respectively, there may be only one terminal adapter circuit 541 for functions of voltage/current regulation or limiting, types of protection, current/voltage regulation, etc. within rectifying circuits 510 and 540, omitting another terminal adapter circuit 541 within rectifying circuit 510 or 540.

FIG. 15A is a schematic diagram of a terminal adapter circuit according to an embodiment. Referring to FIG. 15A, terminal adapter circuit 641 comprises a capacitor 642 having an end connected to pins 501 and 502, and another end connected to half-wave node 819. Capacitor 642 has an equivalent impedance to an AC signal, which impedance increases as the frequency of the AC signal decreases, and decreases as the frequency increases. Therefore, capacitor 642 in terminal adapter circuit 641 in this embodiment works as a high-pass filter. Further, terminal adapter circuit 641 is connected in series to an LED unit in the LED tube lamp, producing an equivalent impedance of terminal adapter circuit 641 to perform a current/voltage limiting function on the LED unit, thereby preventing damaging of the LED unit by an excessive voltage across and/or current in the LED unit. In addition, choosing the value of capacitor 642 according to the frequency of the AC signal can further enhance voltage/current regulation.

Terminal adapter circuit 641 may further include a capacitor 645 and/or capacitor 646. Capacitor 645 has an end connected to half-wave node 819, and another end connected to pin 503. Capacitor 646 has an end connected to half-wave node 819, and another end connected to pin 504. For example, half-wave node 819 may be a common connective node between capacitors 645 and 646. And capacitor 642 acting as a current regulating capacitor is coupled to the common connective node and pins 501 and 502. In such a structure, series-connected capacitors 642 and 645 exist between one of pins 501 and 502 and pin 503, and/or series-connected capacitors 642 and 646 exist between one of pins 501 and 502 and pin 504. Through equivalent impedances of series-connected capacitors, voltages from the AC signal are divided. Referring to FIGS. 13D and 15A, according to ratios between equivalent impedances of the series-connected capacitors, the voltages respectively across capacitor 642 in rectifying circuit 510, filtering circuit 520, and LED lighting module 530 can be controlled, making the current flowing through an LED module in LED lighting module 530 being limited within a current rating, and then protecting/preventing filtering circuit 520 and LED lighting module 530 from being damaged by excessive voltages.

FIG. 15B is a schematic diagram of a terminal adapter circuit according to an embodiment. Referring to FIG. 15B, terminal adapter circuit 741 comprises capacitors 743 and 744. Capacitor 743 has an end connected to pin 501, and another end connected to half-wave node 819. Capacitor 744 has an end connected to pin 502, and another end connected to half-wave node 819. Compared to terminal adapter circuit 641 in FIG. 15A, terminal adapter circuit 741 has capacitors 743 and 744 in place of capacitor 642. Capacitance values of capacitors 743 and 744 may be the same as each other, or may differ from each other depending on the magnitudes of signals to be received at pins 501 and 502.

Similarly, terminal adapter circuit 741 may further comprise a capacitor 745 and/or a capacitor 746, respectively connected to pins 503 and 504. For example, each of pins 501 and 502 and each of pins 503 and 504 may be connected in series to a capacitor, to achieve the functions of voltage division and other protections.

FIG. 15C is a schematic diagram of the terminal adapter circuit according to an embodiment. Referring to FIG. 15C, terminal adapter circuit 841 comprises capacitors 842, 843, and 844. Capacitors 842 and 843 are connected in series between pin 501 and half-wave node 819. Capacitors 842 and 844 are connected in series between pin 502 and half-wave node 819. In such a circuit structure, if any one of capacitors 842, 843, and 844 is shorted, there is still at least one capacitor (of the other two capacitors) between pin 501 and half-wave node 819 and between pin 502 and half-wave node 819, which performs a current-limiting function. Therefore, in the event that a user accidentally gets an electric shock, this circuit structure will prevent an excessive current flowing through and then seriously hurting the body of the user.

Similarly, terminal adapter circuit 841 may further comprise a capacitor 845 and/or a capacitor 846, respectively connected to pins 503 and 504. For example, each of pins 501 and 502 and each of pins 503 and 504 may be connected in series to a capacitor, to achieve the functions of voltage division and other protections.

FIG. 15D is a schematic diagram of the terminal adapter circuit according to an embodiment. Referring to FIG. 15D, terminal adapter circuit 941 comprises fuses 947 and 948. Fuse 947 has an end connected to pin 501, and another end connected to half-wave node 819. Fuse 948 has an end connected to pin 502, and another end connected to half-wave node 819. With the fuses 947 and 948, when the current through each of pins 501 and 502 exceeds a current rating of a corresponding connected fuse 947 or 948, the corresponding fuse 947 or 948 will accordingly melt and then break the circuit to achieve overcurrent protection.

Each of the embodiments of the terminal adapter circuits as in rectifying circuits 510 and 810 coupled to pins 501 and 502 and shown and explained above can be used or included in the rectifying circuit 540 shown in FIG. 13D, as when conductive pins 503 and 504 and conductive pins 501 and 502 are interchanged in position.

Capacitance values of the capacitors in the embodiments of the terminal adapter circuits shown and described above are in some embodiments in the range, for example, of about 100 pF-100 nF. Also, a capacitor used in embodiments may be equivalently replaced by two or more capacitors connected in series or parallel. For example, each of capacitors 642 and 842 may be replaced by two series-connected capacitors, one having a capacitance value chosen from the range, for example of about 1.0 nF to about 2.5 nF (such as, for example, about 1.5 nF), and the other having a capacitance value chosen from the range, for example of about 1.5 nF to about 3.0 nF (such as, for example, about 2.2 nF).

FIG. 16A is a block diagram of a filtering circuit according to an embodiment. Rectifying circuit 510 is shown in FIG. 16A for illustrating its connection with other components, without intending filtering circuit 520 to include rectifying circuit 510. Referring to FIG. 16A, filtering circuit 520 includes a filtering unit 523 coupled to rectifying output terminals 511 and 512 to receive, and to filter out ripples of, a rectified signal from rectifying circuit 510, thereby outputting a filtered signal whose waveform is smoother than the rectified signal. Filtering circuit 520 may further comprise another filtering unit 524 coupled between a rectifying circuit and a pin, which are for example rectifying circuit 510 and pin 501, rectifying circuit 510 and pin 502, rectifying circuit 540 and pin 503, or rectifying circuit 540 and pin 504. Filtering unit 524 is for filtering of a specific frequency, in order to filter out a specific frequency component of an external driving signal. In this embodiment of FIG. 16A, filtering unit 524 is coupled between rectifying circuit 510 and pin 501. Filtering circuit 520 may further comprise another filtering unit 525 coupled between one of pins 501 and 502 and a diode of rectifying circuit 510, or between one of pins 503 and 504 and a diode of rectifying circuit 540, for reducing or filtering out electromagnetic interference (EMI). In this embodiment, filtering unit 525 is coupled between pin 501 and a diode (not shown in FIG. 16A) of rectifying circuit 510. Since filtering units 524 and 525 may be present or omitted depending on actual circumstances of their uses, they are depicted by a dotted line in FIG. 16A.

FIG. 16B is a schematic diagram of a filtering unit according to an embodiment. Referring to FIG. 16B, filtering unit 623 includes a capacitor 625 having an end coupled to output terminal 511 and a filtering output terminal 521 and another end coupled to output terminal 512 and a filtering output terminal 522, and is configured to low-pass filter a rectified signal from output terminals 511 and 512, so as to filter out high-frequency components of the rectified signal and thereby output a filtered signal at output terminals 521 and 522.

FIG. 16C is a schematic diagram of a filtering unit according to an embodiment. Referring to FIG. 16C, filtering unit 723 comprises a pi filter circuit including a capacitor 725, an inductor 726, and a capacitor 727. As is well known, a pi filter circuit looks like the symbol π in its shape or structure. Capacitor 725 has an end connected to output terminal 511 and coupled to output terminal 521 through inductor 726, and has another end connected to output terminals 512 and 522. Inductor 726 is coupled between output terminals 511 and 521. Capacitor 727 has an end connected to output terminal 521 and coupled to output terminal 511 through inductor 726, and has another end connected to output terminals 512 and 522.

As seen between output terminals 511 and 512 and output terminals 521 and 522, filtering unit 723 compared to filtering unit 623 in FIG. 16B additionally has inductor 726 and capacitor 727, which are like capacitor 725 in performing low-pass filtering. Therefore, filtering unit 723 in this embodiment compared to filtering unit 623 in FIG. 16B has a better ability to filter out high-frequency components to output a filtered signal with a smoother waveform.

Inductance values of inductor 726 in the embodiment described above are chosen in some embodiments in the range of about 10 nH to about 10 mH. And capacitance values of capacitors 625, 725, and 727 in the embodiments described above are chosen in some embodiments in the range, for example, of about 100 pF to about 1 uF.

FIG. 16D is a schematic diagram of the filtering unit according to an embodiment. Referring to FIG. 16D, filtering unit 824 includes a capacitor 825 and an inductor 828 connected in parallel. Capacitor 825 has an end coupled to pin 501, and another end coupled to rectifying output terminal 511, and is configured to high-pass filter an external driving signal input at pin 501, so as to filter out low-frequency components of the external driving signal. Inductor 828 has an end coupled to pin 501 and another end coupled to rectifying output terminal 511, and is configured to low-pass filter an external driving signal input at pin 501, so as to filter out high-frequency components of the external driving signal. Therefore, the combination of capacitor 825 and inductor 828 works to present high impedance to an external driving signal at one or more specific frequencies. In some embodiments, the parallel-connected capacitor and inductor present a peak equivalent impedance to the external driving signal at a specific frequency.

Through appropriately choosing a capacitance value of capacitor 825 and an inductance value of inductor 828, a center frequency f on the high-impedance band may be set at a specific value given by

${f = \frac{1}{2\pi\sqrt{LC}}},$ where L denotes inductance of inductor 828 and C denotes capacitance of capacitor 825. The center frequency may be in the range of, for example, about 20˜30 kHz. In some embodiments, the center frequency may be about 25 kHz. And an LED lamp with filtering unit 824 is able to be certified under safety standards, for a specific center frequency, as provided by Underwriters Laboratories (UL).

It's worth noting that filtering unit 824 may further comprise a resistor 829, coupled between pin 501 and filtering output terminal 511. In FIG. 16D, resistor 829 is connected in series to the parallel-connected capacitor 825 and inductor 828. For example, resistor 829 may be coupled between pin 501 and parallel-connected capacitor 825 and inductor 828, or may be coupled between filtering output terminal 511 and parallel-connected capacitor 825 and inductor 828. In this embodiment, resistor 829 is coupled between pin 501 and parallel-connected capacitor 825 and inductor 828. Further, resistor 829 is configured for adjusting the quality factor (Q) of the LC circuit comprising capacitor 825 and inductor 828, to better adapt filtering unit 824 to application environments with different quality factor requirements. Since resistor 829 is an optional component, it is depicted in a dotted line in FIG. 16D.

Capacitance values of capacitor 825 may be, for example, in the range of about 10 nF-2 uF. Inductance values of inductor 828 may be smaller than 2 mH. In some embodiments, inductance values of inductor 828 may be smaller than 1 mH. Resistance values of resistor 829 may be larger than 50 ohms. In some embodiments, resistance values of resistor 829 may be larger than 500 ohms.

Besides the filtering circuits shown and described in the above embodiments, traditional low-pass or band-pass filters can be used as the filtering unit in the filtering circuit.

FIG. 16E is a schematic diagram of a filtering unit according to an embodiment. Referring to FIG. 16E, in this embodiment filtering unit 925 is disposed in rectifying circuit 610 as shown in FIG. 14A, and is configured for reducing the EMI (Electromagnetic interference) caused by rectifying circuit 610 and/or other circuits. In this embodiment, filtering unit 925 includes an EMI-reducing capacitor coupled between pin 501 and the anode of rectifying diode 613, and also between pin 502 and the anode of rectifying diode 614, to reduce the EMI associated with the positive half cycle of the AC driving signal received at pins 501 and 502. The EMI-reducing capacitor of filtering unit 925 is also coupled between pin 501 and the cathode of rectifying diode 611, and between pin 502 and the cathode of rectifying diode 612, to reduce the EMI associated with the negative half cycle of the AC driving signal received at pins 501 and 502. In some embodiments, rectifying circuit 610 comprises a full-wave bridge rectifier circuit including four rectifying diodes 611, 612, 613, and 614. The full-wave bridge rectifier circuit has a first filtering node connecting an anode and a cathode respectively of two diodes 613 and 611 of the four rectifying diodes 611, 612, 613, and 614, and a second filtering node connecting an anode and a cathode respectively of the other two diodes 614 and 612 of the four rectifying diodes 611, 612, 613, and 614. And the EMI-reducing capacitor of the filtering unit 925 is coupled between the first filtering node and the second filtering node.

Similarly, with reference to FIGS. 14C, and 15A-15C, any capacitor in each of the circuits in FIGS. 15A-15C is coupled between pins 501 and 502 (or pins 503 and 504) and any diode in FIG. 14C, so any or each capacitor in FIGS. 15A-15C can work as an EMI-reducing capacitor to achieve the function of reducing EMI. For example, rectifying circuit 510 in FIGS. 13B and 13D may comprise a half-wave rectifier circuit including two rectifying diodes and having a half-wave node connecting an anode and a cathode respectively of the two rectifying diodes, and any or each capacitor in FIGS. 15A-15C may be coupled between the half-wave node and at least one of the first pin and the second pin. And rectifying circuit 540 in FIG. 13D may comprise a half-wave rectifier circuit including two rectifying diodes and having a half-wave node connecting an anode and a cathode respectively of the two rectifying diodes, and any or each capacitor in FIGS. 15A-15C may be coupled between the half-wave node and at least one of the third pin and the fourth pin.

It's worth noting that the EMI-reducing capacitor in the embodiment of FIG. 16E may also act as capacitor 825 in filtering unit 824, so that in combination with inductor 828 the capacitor 825 performs the functions of reducing EMI and presenting high impedance to an external driving signal at specific frequencies. For example, when the rectifying circuit comprises a full-wave bridge rectifier circuit, capacitor 825 of filtering unit 824 may be coupled between the first filtering node and the second filtering node of the full-wave bridge rectifier circuit. When the rectifying circuit comprises a half-wave rectifier circuit, capacitor 825 of filtering unit 824 may be coupled between the half-wave node of the half-wave rectifier circuit and at least one of the first pin and the second pin.

FIG. 17A is a schematic diagram of an LED module according to an embodiment. Referring to FIG. 17A, LED module 630 has an anode connected to the filtering output terminal 521, has a cathode connected to the filtering output terminal 522, and comprises at least one LED unit 632. When two or more LED units are included, they are connected in parallel. The anode of each LED unit 632 is connected to, or forms, the anode of LED module 630 and thus is connected to output terminal 521, and the cathode of each LED unit 632 is connected to, or forms, the cathode of LED module 630 and thus is connected to output terminal 522. Each LED unit 632 includes at least one LED 631. When multiple LEDs 631 are included in an LED unit 632, they are connected in series, with the anode of the first LED 631 connected to, or forming, the anode of this LED unit 632, and the cathode of the first LED 631 connected to the next or second LED 631. And the anode of the last LED 631 in this LED unit 632 is connected to the cathode of a previous LED 631, with the cathode of the last LED 631 connected to, or forming, the cathode of this LED unit 632.

According to certain embodiments, LED module 630 may produce a current detection signal S531 reflecting a magnitude of current through LED module 630 and used for controlling or detecting on the LED module 630. As described herein, an LED unit may refer to a single string of LEDs arranged in series, and an LED module may refer to a single LED unit, or a plurality of LED units connected to a same two nodes (e.g., arranged in parallel). For example, the LED light strip 2 described above may be an LED module and/or LED unit.

FIG. 17B is a schematic diagram of an LED module according to one embodiment. Referring to FIG. 17B, LED module 630 has an anode connected to the filtering output terminal 521, has a cathode connected to the filtering output terminal 522, and comprises at least two LED units 732, with the anode of each LED unit 732 connected to, or forming, the anode of LED module 630, and the cathode of each LED unit 732 connected to, or forming, the cathode of LED module 630. Each LED unit 732 includes at least two LEDs 731 connected in the same way as described in FIG. 17A. For example, the anode of the first LED 731 in an LED unit 732 is connected to, or forms, the anode of this LED unit 732 that it is a part of, the cathode of the first LED 731 is connected to the anode of the next or second LED 731, and the cathode of the last LED 731 is connected to, or forms, the cathode of this LED unit 732 that it is a part of. Further, LED units 732 in the LED module 630 are connected to each other in this embodiment. All of the n-th LEDs 731 respectively of the LED units 732 are connected by every anode of every n-th LED 731 in the LED units 732, and by every cathode of every n-th LED 731, where n is a positive integer. In this way, the LEDs in LED module 630 in this embodiment are connected in the form of a mesh.

The number of LEDs 731 included by an LED unit 732 may be in the range of 15-25. In some embodiments, the number of LEDs 731 may be in the range of 18-22.

FIG. 17C is a plan view of a circuit layout of an LED module according to one embodiment. Referring to FIG. 17C, in this embodiment LEDs 831 are connected in the same way as described in FIG. 17B, and three LED units are assumed in LED module 630 and described as follows for illustration. A positive conductive line 834 and a negative conductive line 835 are to receive a driving signal, for supplying power to the LEDs 831. For example, positive conductive line 834 may be coupled to the filtering output terminal 521 of the filtering circuit 520 described above, and negative conductive line 835 coupled to the filtering output terminal 522 of the filtering circuit 520, to receive a filtered signal. For the convenience of illustration, all three of the n-th LEDs 831 respectively of the three LED units are grouped as an LED set 833 in FIG. 17C.

Positive conductive line 834 connects the three first LEDs 831 respectively of the leftmost three LED units, at the anodes on the left sides of the three first LEDs 831 as shown in the leftmost LED set 833 of FIG. 17C. Negative conductive line 835 connects the three last LEDs 831 respectively of the leftmost three LED units, at the cathodes on the right sides of the three last LEDs 831 as shown in the rightmost LED set 833 of FIG. 17C. And of the three LED units, the cathodes of the three first LEDs 831, the anodes of the three last LEDs 831, and the anodes and cathodes of all the remaining LEDs 831 are connected by conductive lines or parts 839, also referred to as internal conductive connectors.

For example, the anodes of the three LEDs 831 in the leftmost LED set 833 may be connected together by positive conductive line 834, and their cathodes may be connected together by a leftmost conductive part 839. The anodes of the three LEDs 831 in the second leftmost LED set 833 are also connected together by the leftmost conductive part 839, whereas their cathodes are connected together by a second, next-leftmost conductive part 839. Since the cathodes of the three LEDs 831 in the leftmost LED set 833 and the anodes of the three LEDs 831 in the second, next-leftmost LED set 833 are connected together by the same leftmost conductive part 839, in each of the three LED units the cathode of the first LED 831 is connected to the anode of the next or second LED 831, with the remaining LEDs 831 also being connected in the same way. Accordingly, all the LEDs 831 of the three LED units are connected to form the mesh as shown in FIG. 17B. The LED module shown in FIG. 17C may form an LED light strip 2 such as described above.

In the embodiment shown in FIG. 17C, the length 836 (e.g., length along a first direction that is a length direction of the LED light strip 2 and lamp tube) of a portion of each conductive part 839 that immediately connects to the anode of an LED 831 is smaller than the length 837 of another portion of each conductive part 839 that immediately connects to the cathode of an LED 831, making the area of the latter portion immediately connecting to the cathode larger than that of the former portion immediately connecting to the anode. The length 837 may be smaller than a length 838 of a portion of each conductive part 839 that immediately connects the cathode of an LED 831 and the anode of the next LED 831, making the area of the portion of each conductive part 839 that immediately connects a cathode and an anode larger than the area of any other portion of each conductive part 839 that immediately connects to only a cathode or an anode of an LED 831. Due to the length differences and area differences, this layout structure improves heat dissipation of the LEDs 831.

In some embodiments, positive conductive line 834 includes a lengthwise portion 834 a, and negative conductive line 835 includes a lengthwise portion 835 a, which are conducive to making the LED module have a positive “+” connective portion and a negative “−” connective portion at each of the two ends of the LED module, as shown in FIG. 17C. Such a layout structure allows for coupling certain of the various circuits of the power supply module of the LED lamp, including e.g. filtering circuit 520 and rectifying circuits 510 and 540, to the LED module through the positive connective portion and/or the negative connective portion at each or both ends of the LED lamp. In some embodiments, the layout structure increases the flexibility in arranging actual circuits in the LED lamp.

FIG. 17D is a plan view of a circuit layout of the LED module according to another embodiment. Referring to FIG. 17D, in this embodiment LEDs 931 are connected in the same way as described in FIG. 17A, and three LED units each including 7 LEDs 931 are assumed in LED module 630 and described as follows for illustration. A positive conductive line 934 and a negative conductive line 935 are to receive a driving signal, for supplying power to the LEDs 931. For example, positive conductive line 934 may be coupled to the filtering output terminal 521 of the filtering circuit 520 described above, and negative conductive line 935 coupled to the filtering output terminal 522 of the filtering circuit 520, to receive a filtered signal. For the convenience of illustration, all seven LEDs 931 of each of the three LED units are grouped as an LED set 932 in FIG. 17D. For example, there are three LED sets 932 corresponding to the three LED units.

Positive conductive line 934 connects to the anode on the left side of the first or leftmost LED 931 of each of the three LED sets 932. Negative conductive line 935 connects to the cathode on the right side of the last or rightmost LED 931 of each of the three LED sets 932. In each LED set 932, of two consecutive LEDs 931 the LED 931 on the left has a cathode connected by a conductive part 939 to an anode of the LED 931 on the right. By such a layout, the LEDs 931 of each LED set 932 are connected in series.

In some embodiments, the conductive part 939 may be used to connect an anode and a cathode respectively of two consecutive LEDs 931. Negative conductive line 935 connects to the cathode of the last or rightmost LED 931 of each of the three LED sets 932. And positive conductive line 934 connects to the anode of the first or leftmost LED 931 of each of the three LED sets 932. Therefore, as shown in FIG. 17D, the length (and thus area) of the conductive part 939 is larger than that of the portion of negative conductive line 935 immediately connecting to a cathode, which length (and thus area) is then larger than that of the portion of positive conductive line 934 immediately connecting to an anode. For example, the length 938 of the conductive part 939 may be larger than the length 937 of the portion of negative conductive line 935 immediately connecting to a cathode of an LED 931, which length 937 is then larger than the length 936 of the portion of positive conductive line 934 immediately connecting to an anode of an LED 931. Such a layout structure improves heat dissipation of the LEDs 931 in LED module 630.

Positive conductive line 934 may include a lengthwise portion 934 a, and negative conductive line 935 may include a lengthwise portion 935 a, which are conducive to making the LED module have a positive “+” connective portion and a negative “−” connective portion at each of the two ends of the LED module, as shown in FIG. 17D. Such a layout structure allows for coupling certain of the various circuits of the power supply module of the LED lamp, including e.g. filtering circuit 520 and rectifying circuits 510 and 540, to the LED module through the positive connective portion 934 a and/or the negative connective portion 935 a at each or both ends of the LED lamp.

The positive conductive lines (834 or 934) may be characterized as including two end terminals at opposite ends, a plurality of pads between the two end terminals and for contacting and/or supplying power to LEDs (e.g., anodes of LEDs), and a wire portion, which may be an elongated conducive line extending along a length of an LED light strip and electrically connecting the two end terminals to the plurality of pads. Similarly, the negative conductive lines (835 or 935) may be characterized as including two end terminals at opposite ends, a plurality of pads between the two end terminals and for contacting and/or supplying power to LEDs (e.g., cathodes of LEDs), and a wire portion, which may be an elongated conducive line extending along a length of an LED light strip and electrically connecting the two end terminals to the plurality of pads. In some embodiments, the layout structure described above increases the flexibility in arranging actual circuits in the LED lamp.

Further, the circuit layouts as shown in FIGS. 17C and 17D may be implemented with a bendable circuit sheet or substrate, which may even be called flexible circuit board. The circuit layouts may be implemented for one of the exemplary LED light strips described previously, for example, to serve as a circuit board or sheet for the LED light strip on which the LED light sources are disposed. For example, the bendable circuit sheet may comprise one conductive layer where positive conductive line 834, including positive lengthwise portion 834 a, negative conductive line 835, including negative lengthwise portion 835 a, and conductive parts 839 shown in FIG. 17C, and positive conductive line 934, positive lengthwise portion 934 a, negative conductive line 935, negative lengthwise portion 935 a, and conductive parts 939 shown in FIG. 17D are formed. For example, the different conductive patterns may be formed by an etching method.

FIG. 17E is a plan view of a circuit layout of an LED module according to another embodiment. The layout structures of the LED module in FIGS. 17E and 17C each correspond to the same way of connecting LEDs 831 as that shown in FIG. 17B, but the layout structure in FIG. 17E comprises two conductive layers, instead of only one conductive layer for forming the circuit layout as shown in FIG. 17C. Referring to FIG. 17E, the main difference from the layout in FIG. 17C is that positive conductive line 834 and negative conductive line 835 have a lengthwise portion 834 a and a lengthwise portion 835 a, respectively, that are formed in a second conductive layer instead. The difference is elaborated as follows.

Referring to FIG. 17E, the bendable circuit sheet of the LED module comprises a first conductive layer 2 a and a second conductive layer 2 c electrically insulated from each other by a dielectric layer 2 b (not shown). Of the two conductive layers, positive conductive line 834, negative conductive line 835, and conductive parts 839 in FIG. 17E are formed in first conductive layer 2 a by the method of etching for electrically connecting the plurality of LED components 831 e.g. in a form of a mesh, whereas positive lengthwise portion 834 a and negative lengthwise portion 835 a are formed in second conductive layer 2 c by etching for electrically connecting to (the filtering output terminal of) the filtering circuit. Further, positive conductive line 834 and negative conductive line 835 in first conductive layer 2 a have via points 834 b and via points 835 b, respectively, for connecting to second conductive layer 2 c. And positive lengthwise portion 834 a and negative lengthwise portion 835 a in second conductive layer 2 c have via points 834 c and via points 835 c, respectively. Via points 834 b are positioned corresponding to via points 834 c, for connecting positive conductive line 834 and positive lengthwise portion 834 a. Via points 835 b are positioned corresponding to via points 835 c, for connecting negative conductive line 835 and negative lengthwise portion 835 a. In some embodiments, the two conductive layers may be connected by forming a hole connecting each via point 834 b and a corresponding via point 834 c, and to form a hole connecting each via point 835 b and a corresponding via point 835 c, with the holes extending through the two conductive layers and the dielectric layer in-between. Positive conductive line 834 and positive lengthwise portion 834 a can be electrically connected, for example, by welding metallic part(s) through the connecting hole(s), and negative conductive line 835 and negative lengthwise portion 835 a can be electrically connected, for example, by welding metallic part(s) through the connecting hole(s).

Similarly, the layout structure of the LED module in FIG. 17D may alternatively have positive lengthwise portion 934 a and negative lengthwise portion 935 a disposed in a second conductive layer, to constitute a two-layer layout structure.

It's worth noting that the thickness of the second conductive layer of a two-layer bendable circuit sheet is in some embodiments larger than that of the first conductive layer, in order to reduce the voltage drop or loss along each of the positive lengthwise portion and the negative lengthwise portion disposed in the second conductive layer. Compared to a one-layer bendable circuit sheet, since a positive lengthwise portion and a negative lengthwise portion are disposed in a second conductive layer in a two-layer bendable circuit sheet, the width (between two lengthwise sides) of the two-layer bendable circuit sheet is or can be reduced. On the same fixture or plate in a production process, the maximum number of bendable circuit sheets each with a shorter width that can be laid together is larger than the maximum number of bendable circuit sheets each with a longer width that can be laid together. In some embodiments, adopting a bendable circuit sheet with a shorter width can increase the efficiency of production of the LED module. And reliability in the production process, such as the accuracy of welding position when welding (materials on) the LED components, can also be improved, because a two-layer bendable circuit sheet can better maintain its shape.

As a variant of the above embodiments, an exemplary LED tube lamp may have at least some of the electronic components of its power supply module disposed on a light strip of the LED tube lamp. For example, the technique of printed electronic circuit (PEC) can be used to print, insert, or embed at least some of the electronic components onto the LED light strip (e.g., as opposed to being on a separate circuit board connected to the LED light strip).

In one embodiment, all electronic components of the power supply module are disposed directly on the LED light strip. For example, the production process may include or proceed with the following steps: preparation of the circuit substrate (e.g. preparation of a flexible printed circuit board); ink jet printing of metallic nano-ink; ink jet printing of active and passive components (as of the power supply module); drying/sintering; ink jet printing of interlayer bumps; spraying of insulating ink; ink jet printing of metallic nano-ink; ink jet printing of active and passive components (to sequentially form the included layers); spraying of surface bond pad(s); and spraying of solder resist against LED components. The production process may be different, however, and still result in some or all electronic components of the power supply module being disposed directly on the LED light strip.

In certain embodiments, if all electronic components of the power supply module are disposed on the light strip, electrical connection between terminal pins of the LED tube lamp and the light strip may be achieved by connecting the pins to conductive lines which are welded to ends of the light strip. In this case, another substrate for supporting the power supply module is not used, thereby allowing of an improved design or arrangement in the end cap(s) of the LED tube lamp. In some embodiments, (components of) the power supply module are disposed at two ends of the light strip, in order to significantly reduce the impact of heat generated from the power supply module's operations on the LED components. In this embodiment, since no substrate other than the light strip is used to support the power supply module in this case, the total amount of welding or soldering can be significantly reduced, improving the general reliability of the power supply module.

Another case is that some of all electronic components of the power supply module, such as some resistors and/or smaller size capacitors, are printed onto the light strip, and some bigger size components, such as some inductors and/or electrolytic capacitors, are disposed in the end cap(s) (e.g., on another substrate). The production process of the light strip in this case may be the same as that described above. And in this case disposing some of all electronic components on the light strip is conducive to achieving a reasonable layout of the power supply module in the LED tube lamp, which may allow of an improved design in the end cap(s).

As a variant embodiment of the above, electronic components of the power supply module may be disposed on the light strip by a method of embedding or inserting, e.g. by embedding the components onto a bendable or flexible light strip. In some embodiments, this embedding may be realized by a method using copper-clad laminates (CCL) for forming a resistor or capacitor; a method using ink related to silkscreen printing; or a method of ink jet printing to embed passive components, wherein an ink jet printer is used to directly print inks to constitute passive components and related functionalities to intended positions on the light strip. Then through treatment by ultraviolet (UV) light or drying/sintering, the light strip is formed where passive components are embedded. The electronic components embedded onto the light strip include for example resistors, capacitors, and inductors. In other embodiments, active components also may be embedded. Through embedding some components onto the light strip, a reasonable layout of the power supply module can be achieved to allow of an improved design in the end cap(s), because the surface area on a printed circuit board used for carrying components of the power supply module is reduced or smaller, and as a result the size, weight, and thickness of the resulting printed circuit board for carrying components of the power supply module is also smaller or reduced. Also in this situation since welding points on the printed circuit board for welding resistors and/or capacitors if they were not to be disposed on the light strip are no longer used, the reliability of the power supply module is improved, in view of the fact that these welding points are most liable to (cause or incur) faults, malfunctions, or failures. Further, the length of conductive lines used for connecting components on the printed circuit board is therefore also reduced, which allows of a more compact layout of components on the printed circuit board and thus improving the functionalities of these components.

Next, methods to produce embedded capacitors and resistors are explained as follows.

Usually, methods for manufacturing embedded capacitors employ or involve a concept called distributed or planar capacitance. The manufacturing process may include the following step(s). On a substrate of a copper layer a very thin insulation layer is applied or pressed, which is then generally disposed between a pair of layers including a power conductive layer and a ground layer. The very thin insulation layer makes the distance between the power conductive layer and the ground layer very short. A capacitance resulting from this structure can also be realized by a conventional technique of a plated-through hole. Basically, this step is used to create this structure comprising a big parallel-plate capacitor on a circuit substrate.

Of products of high electrical capacity, certain types of products employ distributed capacitances, and other types of products employ separate embedded capacitances. Through putting or adding a high dielectric-constant material such as barium titanate into the insulation layer, the high electrical capacity is achieved.

A usual method for manufacturing embedded resistors employ conductive or resistive adhesive. This may include, for example, a resin to which conductive carbon or graphite is added, which may be used as an additive or filler. The additive resin is silkscreen printed to an object location, and is then after treatment laminated inside the circuit board. The resulting resistor is connected to other electronic components through plated-through holes or microvias. Another method is called Ohmega-Ply, by which a two metallic layer structure of a copper layer and a thin nickel alloy layer constitutes a layer resistor relative to a substrate. Then through etching the copper layer and nickel alloy layer, different types of nickel alloy resistors with copper terminals can be formed. These types of resistor are each laminated inside the circuit board.

In one embodiment, conductive wires/lines are directly printed in a linear layout on an inner surface of the LED glass lamp tube, with LED components directly attached on the inner surface and electrically connected by the conductive wires. In some embodiments, the LED components in the form of chips are directly attached over the conductive wires on the inner surface, and connective points are at terminals of the wires for connecting the LED components and the power supply module. After being attached, the LED chips may have fluorescent powder applied or dropped thereon, for producing white light or light of other color by the operating LED tube lamp.

Luminous efficacy of the LED or LED component may be 80 lm/W or above. In some embodiments, luminous efficiency of the LED or LED component may be 120 lm/W or above. Certain more optimal embodiments may include a luminous efficacy of the LED or LED component of 160 lm/W or above. White light emitted by an LED component, such as those in the disclosed embodiments, may be produced by mixing fluorescent powder with the monochromatic light emitted by a monochromatic LED chip. The white light in its spectrum has major wavelength ranges of 430-460 nm and 550-560 nm, or major wavelength ranges of 430-460 nm, 540-560 nm, and 620-640 nm.

FIG. 18A is a block diagram of an LED lamp according to an embodiment. As shown in FIG. 18A, a power supply module of the LED lamp includes rectifying circuits 510 and 540, a filtering circuit 520, and a driving circuit 1530, and an LED lighting module 530 is composed of the driving circuit 1530 and an LED module 630. LED lighting module 530 in this embodiment comprises a driving circuit 1530 and an LED module 630. According to the above description in FIG. 13D, driving circuit 1530 in FIG. 18A comprises a DC-to-DC converter circuit, and is coupled to filtering output terminals 521 and 522 to receive a filtered signal and then perform power conversion for converting the filtered signal into a driving signal at driving output terminals 1521 and 1522. The LED module 630 is coupled to driving output terminals 1521 and 1522 to receive the driving signal for emitting light. In some embodiments, the current of LED module 630 is stabilized at an objective current value. Descriptions of this LED module 630 are the same as those provided above with reference to FIGS. 17A-17D.

It's worth noting that rectifying circuit 540 is an optional element and therefore can be omitted, so it is depicted in a dotted line in FIG. 18A. Accordingly, LED lighting module 530 in embodiments of FIGS. 18A, 18C, and 18E may comprise a driving circuit 1530 and an LED module 630. Therefore, the power supply module of the LED lamp in this embodiment can be used with a single-end power supply coupled to one end of the LED lamp, and can be used with a dual-end power supply coupled to two ends of the LED lamp. With a single-end power supply, examples of the LED lamp include an LED light bulb, a personal area light (PAL), etc.

FIG. 18B is a block diagram of an exemplary driving circuit according to one embodiment. Referring to FIG. 18B, the driving circuit includes a controller 1531, and a conversion circuit 1532 for power conversion based on a current source, for driving the LED module to emit light. Conversion circuit 1532 includes a switching circuit 1535 and an energy storage circuit 1538. And conversion circuit 1532 is coupled to filtering output terminals 521 and 522 to receive and then convert a filtered signal, under the control by controller 1531, into a driving signal at driving output terminals 1521 and 1522 for driving the LED module. Under the control by controller 1531, the driving signal output by conversion circuit 1532 comprises a steady current, making the LED module emitting steady light.

FIG. 18C is a schematic diagram of an exemplary driving circuit according to one embodiment. Referring to FIG. 18C, a driving circuit 1630 in this embodiment comprises a buck DC-to-DC converter circuit having a controller 1631 and a converter circuit. The converter circuit includes an inductor 1632, a diode 1633 for “freewheeling” of current, a capacitor 1634, and a switch 1635. Driving circuit 1630 is coupled to filtering output terminals 521 and 522 to receive and then convert a filtered signal into a driving signal for driving an LED module connected between driving output terminals 1521 and 1522.

In this embodiment, switch 1635 comprises a metal-oxide-semiconductor field-effect transistor (MOSFET) and has a first terminal coupled to the anode of freewheeling diode 1633, a second terminal coupled to filtering output terminal 522, and a control terminal coupled to controller 1631 used for controlling current conduction or cutoff between the first and second terminals of switch 1635. Driving output terminal 1521 is connected to filtering output terminal 521, and driving output terminal 1522 is connected to an end of inductor 1632, which has another end connected to the first terminal of switch 1635. Capacitor 1634 is coupled between driving output terminals 1521 and 1522, to stabilize the voltage between driving output terminals 1521 and 1522. Freewheeling diode 1633 has a cathode connected to driving output terminal 1521.

Next, a description follows as to an exemplary operation of driving circuit 1630.

Controller 1631 is configured for determining when to turn switch 1635 on (in a conducting state) or off (in a cutoff state), according to a current detection signal S535 and/or a current detection signal S531. For example, in some embodiments, controller 1631 is configured to control the duty cycle of switch 1635 being on and switch 1635 being off, in order to adjust the size or magnitude of the driving signal. Current detection signal S535 represents the magnitude of current through switch 1635. Current detection signal S531 represents the magnitude of current through the LED module coupled between driving output terminals 1521 and 1522. The controller 1631 may control the duty cycle of the switch 1635 being on and off, based on, for example, a magnitude of a current detected based on current detection signal S531 or S535. As such, when the magnitude is above a threshold, the switch may be off (cutoff state) for more time, and when magnitude goes below the threshold, the switch may be on (conducting state) for more time. According to any of current detection signal S535 and current detection signal S531, controller 1631 can obtain information on the magnitude of power converted by the converter circuit. When switch 1635 is switched on, a current of a filtered signal is input through filtering output terminal 521, and then flows through capacitor 1634, driving output terminal 1521, the LED module, inductor 1632, and switch 1635, and then flows out from filtering output terminal 522. During this flowing of current, capacitor 1634 and inductor 1632 are performing storing of energy. On the other hand, when switch 1635 is switched off, capacitor 1634 and inductor 1632 perform releasing of stored energy by a current flowing from freewheeling capacitor 1633 to driving output terminal 1521 to make the LED module continuing to emit light.

It's worth noting that capacitor 1634 is an optional element, so it can be omitted and is thus depicted in a dotted line in FIG. 18C. In some application environments, the natural characteristic of an inductor to oppose instantaneous change in electric current passing through the inductor may be used to achieve the effect of stabilizing the current through the LED module, thus omitting capacitor 1634.

FIG. 18D is a schematic diagram of an exemplary driving circuit according to one embodiment. Referring to FIG. 18D, a driving circuit 1730 in this embodiment comprises a boost DC-to-DC converter circuit having a controller 1731 and a converter circuit. The converter circuit includes an inductor 1732, a diode 1733 for “freewheeling” of current, a capacitor 1734, and a switch 1735. Driving circuit 1730 is configured to receive and then convert a filtered signal from filtering output terminals 521 and 522 into a driving signal for driving an LED module coupled between driving output terminals 1521 and 1522.

Inductor 1732 has an end connected to filtering output terminal 521, and another end connected to the anode of freewheeling diode 1733 and a first terminal of switch 1735, which has a second terminal connected to filtering output terminal 522 and driving output terminal 1522. Freewheeling diode 1733 has a cathode connected to driving output terminal 1521. And capacitor 1734 is coupled between driving output terminals 1521 and 1522.

Controller 1731 is coupled to a control terminal of switch 1735, and is configured for determining when to turn switch 1735 on (in a conducting state) or off (in a cutoff state), according to a current detection signal S535 and/or a current detection signal S531. When switch 1735 is switched on, a current of a filtered signal is input through filtering output terminal 521, and then flows through inductor 1732 and switch 1735, and then flows out from filtering output terminal 522. During this flowing of current, the current through inductor 1732 increases with time, with inductor 1732 being in a state of storing energy, while capacitor 1734 enters a state of releasing energy, making the LED module continuing to emit light. On the other hand, when switch 1735 is switched off, inductor 1732 enters a state of releasing energy as the current through inductor 1732 decreases with time. In this state, the current through inductor 1732 then flows through freewheeling diode 1733, capacitor 1734, and the LED module, while capacitor 1734 enters a state of storing energy.

It's worth noting that capacitor 1734 is an optional element, so it can be omitted, as is depicted by the dotted line in FIG. 18D. When capacitor 1734 is omitted and switch 1735 is switched on, the current of inductor 1732 does not flow through the LED module, making the LED module not emit light; but when switch 1735 is switched off, the current of inductor 1732 flows through freewheeling diode 1733 to reach the LED module, making the LED module emit light. Therefore, by controlling the time that the LED module emits light, and the magnitude of current through the LED module, the average luminance of the LED module can be stabilized to be above a defined value, thus also achieving the effect of emitting a steady light.

FIG. 18E is a schematic diagram of an exemplary driving circuit according to one embodiment. Referring to FIG. 18E, a driving circuit 1830 in this embodiment comprises a buck DC-to-DC converter circuit having a controller 1831 and a converter circuit. The converter circuit includes an inductor 1832, a diode 1833 for “freewheeling” of current, a capacitor 1834, and a switch 1835. Driving circuit 1830 is coupled to filtering output terminals 521 and 522 to receive and then convert a filtered signal into a driving signal for driving an LED module connected between driving output terminals 1521 and 1522.

Switch 1835 has a first terminal coupled to filtering output terminal 521, a second terminal coupled to the cathode of freewheeling diode 1833, and a control terminal coupled to controller 1831 to receive a control signal from controller 1831 for controlling current conduction or cutoff between the first and second terminals of switch 1835. The anode of freewheeling diode 1833 is connected to filtering output terminal 522 and driving output terminal 1522. Inductor 1832 has an end connected to the second terminal of switch 1835, and another end connected to driving output terminal 1521. Capacitor 1834 is coupled between driving output terminals 1521 and 1522, to stabilize the voltage between driving output terminals 1521 and 1522.

Controller 1831 is configured for controlling when to turn switch 1835 on (in a conducting state) or off (in a cutoff state), according to a current detection signal S535 and/or a current detection signal S531. When switch 1835 is switched on, a current of a filtered signal is input through filtering output terminal 521, and then flows through switch 1835, inductor 1832, and driving output terminals 1521 and 1522, and then flows out from filtering output terminal 522. During this flowing of current, the current through inductor 1832 and the voltage of capacitor 1834 both increase with time, so inductor 1832 and capacitor 1834 are in a state of storing energy. On the other hand, when switch 1835 is switched off, inductor 1832 is in a state of releasing energy and thus the current through it decreases with time. In this case, the current through inductor 1832 circulates through driving output terminals 1521 and 1522, freewheeling diode 1833, and back to inductor 1832.

It's worth noting that capacitor 1834 is an optional element, so it can be omitted and is thus depicted in a dotted line in FIG. 18E. When capacitor 1834 is omitted, no matter whether switch 1835 is turned on or off, the current through inductor 1832 will flow through driving output terminals 1521 and 1522 to drive the LED module to continue emitting light.

FIG. 18F is a schematic diagram of an exemplary driving circuit according to one embodiment. Referring to FIG. 18F, a driving circuit 1930 in this embodiment comprises a buck DC-to-DC converter circuit having a controller 1931 and a converter circuit. The converter circuit includes an inductor 1932, a diode 1933 for “freewheeling” of current, a capacitor 1934, and a switch 1935. Driving circuit 1930 is coupled to filtering output terminals 521 and 522 to receive and then convert a filtered signal into a driving signal for driving an LED module connected between driving output terminals 1521 and 1522.

Inductor 1932 has an end connected to filtering output terminal 521 and driving output terminal 1522, and another end connected to a first end of switch 1935. Switch 1935 has a second end connected to filtering output terminal 522, and a control terminal connected to controller 1931 to receive a control signal from controller 1931 for controlling current conduction or cutoff of switch 1935. Freewheeling diode 1933 has an anode coupled to a node connecting inductor 1932 and switch 1935, and a cathode coupled to driving output terminal 1521. Capacitor 1934 is coupled to driving output terminals 1521 and 1522, to stabilize the driving of the LED module coupled between driving output terminals 1521 and 1522.

Controller 1931 is configured for controlling when to turn switch 1935 on (in a conducting state) or off (in a cutoff state), according to a current detection signal S531 and/or a current detection signal S535. When switch 1935 is turned on, a current is input through filtering output terminal 521, and then flows through inductor 1932 and switch 1935, and then flows out from filtering output terminal 522. During this flowing of current, the current through inductor 1932 increases with time, so inductor 1932 is in a state of storing energy; but the voltage of capacitor 1934 decreases with time, so capacitor 1934 is in a state of releasing energy to keep the LED module continuing to emit light. On the other hand, when switch 1935 is turned off, inductor 1932 is in a state of releasing energy and its current decreases with time. In this case, the current through inductor 1932 circulates through freewheeling diode 1933, driving output terminals 1521 and 1522, and back to inductor 1932. During this circulation, capacitor 1934 is in a state of storing energy and its voltage increases with time.

It's worth noting that capacitor 1934 is an optional element, so it can be omitted, as is depicted by the dotted line in FIG. 18F. When capacitor 1934 is omitted and switch 1935 is turned on, the current through inductor 1932 doesn't flow through driving output terminals 1521 and 1522, thereby making the LED module not emit light. On the other hand, when switch 1935 is turned off, the current through inductor 1932 flows through freewheeling diode 1933 and then the LED module to make the LED module emit light. Therefore, by controlling the time that the LED module emits light, and the magnitude of current through the LED module, the average luminance of the LED module can be stabilized to be above a defined value, achieving the effect of emitting a steady light.

FIG. 18G is a block diagram of an exemplary driving circuit according to one embodiment. Referring to FIG. 18G, the driving circuit includes a controller 2631, and a conversion circuit 2632 for power conversion based on an adjustable current source, for driving the LED module to emit light. Conversion circuit 2632 includes a switching circuit 2635 and an energy storage circuit 2638. And conversion circuit 2632 is coupled to filtering output terminals 521 and 522 to receive and then convert a filtered signal, under the control by controller 2631, into a driving signal at driving output terminals 1521 and 1522 for driving the LED module. Controller 2631 is configured to receive a current detection signal S535 and/or a current detection signal S539, for controlling or stabilizing the driving signal output by conversion circuit 2632 to be above an objective current value. Current detection signal S535 represents the magnitude of current through switching circuit 2635. Current detection signal S539 represents the magnitude of current through energy storage circuit 2638, which current may be e.g. an inductor current in energy storage circuit 2638 or a current output at driving output terminal 1521. Any of current detection signal S535 and current detection signal S539 can represent the magnitude of current Iout provided by the driving circuit from driving output terminals 1521 and 1522 to the LED module. Controller 2631 is coupled to filtering output terminal 521 for setting the objective current value according to the voltage Vin at filtering output terminal 521. Therefore, the current Tout provided by the driving circuit or the objective current value can be adjusted corresponding to the magnitude of the voltage Vin of a filtered signal output by a filtering circuit.

It's worth noting that current detection signals S535 and S539 can be generated by measuring current through a resistor or induced by an inductor. For example, a current can be measured according to a voltage drop across a resistor in conversion circuit 2632 the current flows through, or which arises from a mutual induction between an inductor in conversion circuit 2632 and another inductor in its energy storage circuit 2638.

The above driving circuit structures are especially suitable for an application environment in which the external driving circuit for the LED tube lamp includes electronic ballast. An electronic ballast is equivalent to a current source whose output power is not constant. In an internal driving circuit as shown in each of FIGS. 18C-18F, power consumed by the internal driving circuit relates to or depends on the number of LEDs in the LED module, and could be regarded as constant. When the output power of the electronic ballast is higher than power consumed by the LED module driven by the driving circuit, the output voltage of the ballast will increase continually, causing the level of an AC driving signal received by the power supply module of the LED lamp to continually increase, so as to risk damaging the ballast and/or components of the power supply module due to their voltage ratings being exceeded. On the other hand, when the output power of the electronic ballast is lower than power consumed by the LED module driven by the driving circuit, the output voltage of the ballast and the level of the AC driving signal will decrease continually so that the LED tube lamp fail to normally operate.

It's worth noting that the power needed for an LED lamp to work is already lower than that needed for a fluorescent lamp to work. If a conventional control mechanism of e.g. using a backlight module to control the LED luminance is used with a conventional driving system of e.g. a ballast, a problem will probably arise of mismatch or incompatibility between the output power of the external driving system and the power needed by the LED lamp. This problem may even cause damaging of the driving system and/or the LED lamp. To prevent or reduce this problem, using e.g. the power/current adjustment method described above in FIG. 18G enables the LED (tube) lamp to be better compatible with traditional fluorescent lighting systems.

FIG. 18H is a graph illustrating the relationship between the voltage Vin and the objective current value Tout according to an embodiment. In FIG. 18H, the variable Vin is on the horizontal axis, and the variable Tout is on the vertical axis. In some cases, when the level of the voltage Vin of a filtered signal is between the upper voltage limit VH and the lower voltage limit VL, the objective current value Tout will be about an initial objective current value. The upper voltage limit VH is higher than the lower voltage limit VL. When the voltage Vin increases to be higher than the upper voltage limit VH, the objective current value Tout will increase with the increasing of the voltage Vin. During this stage, in certain embodiments, the slope of the relationship curve increases with the increasing of the voltage Vin. When the voltage Vin of a filtered signal decreases to be below the lower voltage limit VL, the objective current value Tout will decrease with the decreasing of the voltage Vin. During this stage, in certain embodiments, the slope of the relationship curve decreases with the decreasing of the voltage Vin. For example, during the stage when the voltage Vin is higher than the upper voltage limit VH or lower than the lower voltage limit VL, the objective current value Tout is in some embodiments a function of the voltage Vin to the power of 2 or above, in order to make the rate of increase/decrease of the consumed power higher than the rate of increase/decrease of the output power of the external driving system. In some embodiments, adjustment of the objective current value Tout is a function of the filtered voltage Vin to the power of 2 or above.

In another case, when the voltage Vin of a filtered signal is between the upper voltage limit VH and the lower voltage limit VL, the objective current value Tout of the LED lamp will vary, increase or decrease, linearly with the voltage Vin. During this stage, when the voltage Vin is at the upper voltage limit VH, the objective current value Tout will be at the upper current limit IH. When the voltage Vin is at the lower voltage limit VL, the objective current value Tout will be at the lower current limit IL. The upper current limit IH is larger than the lower current limit IL. And when the voltage Vin is between the upper voltage limit VH and the lower voltage limit VL, the objective current value Tout will be a function of the voltage Vin to the power of 1.

With the designed relationship in FIG. 18H, when the output power of the ballast is higher than the power consumed by the LED module driven by the driving circuit, the voltage Vin will increase with time to exceed the upper voltage limit VH. When the voltage Vin is higher than the upper voltage limit VH, the rate of increase of the consumed power of the LED module is higher than that of the output power of the electronic ballast, and the output power and the consumed power will be balanced or equal when the voltage Vin is at a high balance voltage value VH+ and the current Tout is at a high balance current value IH+. In this case, the high balance voltage value VH+ is larger than the upper voltage limit VH, and the high balance current value IH+ is larger than the upper current limit IH. On the other hand, when the output power of the ballast is lower than the power consumed by the LED module driven by the driving circuit, the voltage Vin will decrease to be below the lower voltage limit VL. When the voltage Vin is lower than the lower voltage limit VL, the rate of decrease of the consumed power of the LED module is higher than that of the output power of the electronic ballast, and the output power and the consumed power will be balanced or equal when the voltage Vin is at a low balance voltage value VL− and the objective current value Tout is at a low balance current value IL−. In this case, the low balance voltage value VL− is smaller than the lower voltage limit VL, and the low balance current value IL− is smaller than the lower current limit IL.

In some embodiments, the lower voltage limit VL is defined to be around 90% of the lowest output power of the electronic ballast, and the upper voltage limit VH is defined to be around 110% of its highest output power. Taking a common AC powerline with a voltage range of 100-277 volts and a frequency of 60 Hz as an example, the lower voltage limit VL may be set at 90 volts (=100*90%), and the upper voltage limit VH may be set at 305 volts (=277*110%).

A short circuit board may be included in at least one of the two end caps on which to dispose part or all of the power supply. The short circuit board may include a first short circuit substrate and a second short circuit substrate respectively connected to two terminal portions of a long circuit sheet disposed in the lamp tube, and electronic components of the power supply module may be respectively disposed on the first short circuit substrate and the second short circuit substrate. The first short circuit substrate and the second short circuit substrate may have roughly the same length, or different lengths. In general, one of the two short circuit substrates has a length that is about 30%-80% of the length of the other short circuit substrate. In some embodiments the length of the first short circuit substrate is about ⅓ ˜⅔ of the length of the second short circuit substrate. For example, in one embodiment, the length of the first short circuit substrate may be about half the length of the second short circuit substrate. The length of the second short circuit substrate may be, for example in the range of about 15 mm to about 65 mm, depending on actual application occasions. In certain embodiments, the first short circuit substrate is disposed in an end cap at an end of the LED tube lamp, and the second short circuit substrate is disposed in another end cap at the opposite end of the LED tube lamp.

The short circuit board may have a length generally of about 15 mm to about 40 mm, while the long circuit sheet (e.g., including the flexible circuit of the light strip 2) may have a length generally of about 800 mm to about 2800 mm. In some embodiments, the short circuit board may have a length of about 19 mm to about 36 mm, and the long circuit sheet may have a length of about 1200 mm to about 2400 mm. In some embodiments, a ratio of the length of the short circuit board to the length of the long circuit sheet ranges from about 1:20 to about 1:200.

For example, capacitors of the driving circuit, such as capacitors 1634, 1734, 1834, and 1934 in FIGS. 18C-18F, in practical use may include two or more capacitors connected in parallel. Some or all capacitors of the driving circuit in the power supply module may be arranged on the first short circuit substrate of a short circuit board, while other components such as the rectifying circuit, filtering circuit, inductor(s) of the driving circuit, controller(s), switch(es), diodes, etc. are arranged on the second short circuit substrate of a short circuit board. Since inductors, controllers, switches, etc. are electronic components with higher temperature, arranging some or all capacitors on a circuit substrate separate or away from the circuit substrate(s) of high-temperature components helps prevent the working life of capacitors (especially electrolytic capacitors) from being negatively affected by the high-temperature components, thereby improving the reliability of the capacitors. Further, the physical separation between the capacitors and both the rectifying circuit and filtering circuit also contributes to reducing the problem of EMI.

In some embodiments, the driving circuit has power conversion efficiency of 80% or above. In some embodiments, the driving circuit may have a power conversion efficiency of 90% or above (such as, for example, 92% or above). Therefore, without the driving circuit, luminous efficacy of the LED lamp may be 120 lm/W or above. In some embodiments, without the driving circuit, luminous efficacy of the LED lamp may be 160 lm/W or above. On the other hand, with the driving circuit in combination with the LED component(s), luminous efficacy of the LED lamp may be 120 lm/W*90% (i.e., 108 lm/W) or above. In some embodiments, with the driving circuit in combination with the LED component(s), luminous efficacy of the LED lamp may be 160 lm/W*92% (i.e., 147.2 lm/W) or above.

In view of the fact that the diffusion film or layer in an LED tube lamp has light transmittance of 85% or above, luminous efficacy of the LED tube lamp is in some embodiments 108 lm/W*85%=91.8 lm/W or above, and may be, in some more effective embodiments, 147.21 m/W*85%=125.121 m/W.

Referring to FIG. 19A, a block diagram of an LED tube lamp including a power supply module in accordance with certain embodiments is illustrated. Compared to the LED lamp shown in FIG. 13D, the LED tube lamp of FIG. 19A comprises two rectifying circuits 510 and 540, a filtering circuit 520, and an LED lighting module 530, and further comprises an installation detection module 2520. The installation detection module 2520 is coupled to the rectifying circuit 510 (and/or the rectifying circuit 540) via an installation detection terminal 2521 and is coupled to the filtering circuit 520 via an installation detection terminal 2522. The installation detection module 2520 detects the signal passing through the installation detection terminals 2521 and 2522 and determines whether to cut off an LED driving signal (e.g., an external driving signal) passing through the LED tube lamp based on the detected result. The installation detection module includes circuitry configured to perform these steps, and thus may be referred to as an installation detection circuit, or more generally as a detection circuit or cut-off circuit. When an LED tube lamp is not yet installed on a lamp socket or holder, or in some cases if it is not installed properly or is only partly installed (e.g., one side is connected to a lamp socket, but not the other side yet), the installation detection module 2520 detects a smaller current and determines the signal is passing through a high impedance. In this case, in certain embodiments, the installation detection circuit 2520 is in a cut-off state to make the LED tube lamp stop working. Otherwise, the installation detection module 2520 determines that the LED tube lamp has already been installed on the lamp socket or holder, and it keeps on conducting to make the LED tube lamp working normally.

For example, in some embodiments, when a current passing through the installation detection terminals is greater than or equal to a specific, defined installation current (or a current value), which may indicate that the current supplied to the lighting module 530 is greater than or equal to a specific, defined operating current, the installation detection module is conductive to make the LED tube lamp operate in a conductive state. For example, a current greater than or equal to the specific current value may indicate that the LED tube lamp has correctly or properly been installed in the lamp socket or holder. When the current passing through the installation detection terminals is smaller than the specific, defined installation current (or the current value), which may indicate that the current supplied to the lighting module 530 is less than a specific, defined operating current, the installation detection module cuts off current to make the LED tube lamp enter in a non-conducting state based on determining that the LED tube lamp has been not installed in, or does not properly connect to, the lamp socket or holder. In certain embodiments, the installation detection module 2520 determines conducting or cutting off based on the impedance detection to make the LED tube lamp operate in a conducting state or enter non-conducting state. The LED tube lamp operating in a conducting state may refer to the LED tube lamp including a sufficient current passing through the LED module to cause the LED light sources to emit light. The LED tube lamp operating in a cut-off state may refer to the LED tube lamp including an insufficient current or no current passing through the LED module so that the LED light sources do not emit light. Accordingly, the occurrence of electric shock caused by touching the conductive part of the LED tube lamp which is incorrectly installed on the lamp socket or holder can be better avoided.

Referring to FIG. 19B, a block diagram of an installation detection module in accordance with certain embodiments is illustrated. The installation detection module includes a switch circuit 2580, a detection pulse generating module 2540, a detection result latching circuit 2560, and a detection determining circuit 2570. Certain of these circuits or modules may be referred to as first, second, third, etc., circuits as a naming convention to differentiate them from each other.

The detection determining circuit 2570 is coupled to and detects the signal between the installation detection terminals 2521 (through a switch circuit coupling terminal 2581 and the switch circuit 2580) and 2522. It is also coupled to the detection result latching circuit 2560 via a detection result terminal 2571 to transmit the detection result signal. The detection determining circuit 2570 may be configured to detect a current passing through terminals 2521 and 2522 (e.g., to detect whether the current is above or below a specific value).

The detection pulse generating module 2540 is coupled to the detection result latching circuit 2560 via a pulse signal output terminal 2541, and generates a pulse signal to inform the detection result latching circuit 2560 of a time point for latching (storing) the detection result. For example, the detection pulse generating module 2540 may be a circuit configured to generate a signal that causes a latching circuit, such as the detection result latching circuit 2560 to enter and remain in a state that corresponds to one of a conducting state or a cut-off state for the LED tube lamp. The detection result latching circuit 2560 stores the detection result according to the detection result signal (or detection result signal and pulse signal), and transmits or provides the detection result to the switch circuit 2580 coupled to the detection result latching circuit 2560 via a detection result latching terminal 2561. The switch circuit 2580 controls the state between conducting or cut off between the installation detection terminals 2521 and 2522 according to the detection result.

Referring to FIG. 19C, a block diagram of a detection pulse generating module in accordance with certain embodiments is illustrated. A detection pulse generating module 2640 may be a circuit that includes multiple capacitors 2642, 2645, and 2646, multiple resistors 2643, 2647, and 2648, two buffers 2644, and 2651, an inverter 2650, a diode 2649, and an OR gate 2652. With use or operation, the capacitor 2642 and the resistor 2643 connect in series between a driving voltage (e.g., a driving voltage source, which may be a node of a power supply), such as VCC usually defined as a high logic level voltage, and a reference voltage (or potential), such as ground potential in this embodiment. The connection node between the capacitor 2642 and the resistor 2643 is coupled to an input terminal of the buffer 2644. The resistor 2647 is coupled between the driving voltage, e.g., VCC, and an input terminal of the inverter 2650. The resistor 2648 is coupled between an input terminal of the buffer 2651 and the reference voltage, e.g. ground potential in this embodiment. An anode of the diode 2649 is grounded and a cathode thereof is coupled to the input terminal of the buffer 2651. First ends of the capacitors 2645 and 2646 are jointly coupled to an output terminal of the buffer 2644, and second, opposite ends of the capacitors 2645 and 2646 are respectively coupled to the input terminal of the inverter 2650 and the input terminal of the buffer 2651. An output terminal of the inverter 2650 and an output terminal of the buffer 2651 are coupled to two input terminals of the OR gate 2652. According to certain embodiments, the voltage (or potential) for “high logic level” and “low logic level” mentioned in this specification are all relative to another voltage (or potential) or a certain reference voltage (or potential) in circuits, and further may be described as “logic high logic level” and “logic low logic level.”

When an end cap of an LED tube lamp is inserted into a lamp socket and the other end cap thereof is electrically coupled to a human body, or when both end caps of the LED tube lamp are inserted into the lamp socket, the LED tube lamp is conductive with electricity. At this moment, the installation detection module enters a detection stage. The voltage on the connection node of the capacitor 2642 and the resistor 2643 is high initially (equals to the driving voltage, VCC) and decreases with time to zero finally. The input terminal of the buffer 2644 is coupled to the connection node of the capacitor 2642 and the resistor 2643, so the buffer 2644 outputs a high logic level signal at the beginning and changes to output a low logic level signal when the voltage on the connection node of the capacitor 2642 and the resistor 2643 decreases to a low logic trigger logic level. As a result, the buffer 2644 is configured to produce an input pulse signal and then remain in a low logic level thereafter (stops outputting the input pulse signal.) The width for the input pulse signal may be described as equal to one (initial setting) time period, which is determined by the capacitance value of the capacitor 2642 and the resistance value of the resistor 2643.

Next, the operations for the buffer 2644 to produce the pulse signal with the initial setting time period will be described below. Since the voltage on a first end of the capacitor 2645 and on a first end of the resistor 2647 is equal to the driving voltage VCC, the voltage on the connection node of both of them is also a high logic level. The first end of the resistor 2648 is grounded and the first end of the capacitor 2646 receives the pulse signal from the buffer 2644, so the connection node of the capacitor 2646 and the resistor 2648 has a high logic level voltage at the beginning but this voltage decreases with time to zero (in the meantime, the capacitor stores the voltage being equal to or approaching the driving voltage VCC.) Accordingly, initially the inverter 2650 outputs a low logic level signal and the buffer 2651 outputs a high logic level signal, and hence the OR gate 2652 outputs a high logic level signal (a first pulse signal) at the pulse signal output terminal 2541. At this moment, the detection result latching circuit 2560 stores the detection result for the first time according to the detection result signal and the pulse signal. During that initial pulse time period, detection pulse generating module 2540 outputs a high logic level signal, which results in the detection result latching circuit 2560 outputting the result of that high logic level signal.

When the voltage on the connection node of the capacitor 2646 and the resistor 2648 decreases to the low logic trigger logic level, the buffer 2651 changes to output a low logic level signal to make the OR gate 2652 output a low logic level signal at the pulse signal output terminal 2541 (stops outputting the first pulse signal.) The width of the first pulse signal output from the OR gate 2652 is determined by the capacitance value of the capacitor 2646 and the resistance value of the resistor 2648.

The operation after the buffer 2644 stops outputting the pulse signal is described as below. For example, the operation may be initially in an operating stage. Since the capacitor 2646 stores the voltage being almost equal to the driving voltage VCC, and when the buffer 2644 instantaneously changes its output from a high logic level signal to a low logic level signal, the voltage on the connection node of the capacitor 2646 and the resistor 2648 is below zero but will be pulled up to zero by the diode 2649 rapidly charging the capacitor. Therefore, the buffer 2651 still outputs a low logic level signal.

On the other hand, when the buffer 2644 instantaneously changes its output from a high logic level signal to a low logic level signal, the voltage on the one end of the capacitor 2645 also changes from the driving voltage VCC to zero instantly. This makes the connection node of the capacitor 2645 and the resistor 2647 have a low logic level signal. At this moment, the output of the inverter 2650 changes to a high logic level signal to make the OR gate output a high logic level signal (a second pulse signal.) The detection result latching circuit 2560 stores the detection result for a second time according to the detection result signal and the pulse signal. Next, the driving voltage VCC charges the capacitor 2645 through the resistor 2647 to make the voltage on the connection node of the capacitor 2645 and the resistor 2647 increase with time to the driving voltage VCC. When the voltage on the connection node of the capacitor 2645 and the resistor 2647 increases to reach a high logic trigger logic level, the inverter 2650 outputs a low logic level signal again to make the OR gate 2652 stop outputting the second pulse signal. The width of the second pulse signal is determined by the capacitance value of the capacitor 2645 and the resistance value of the resistor 2647.

As those mentioned above, in certain embodiments, the detection pulse generating module 2640 generates two high logic level pulse signals in the detection stage, which are the first pulse signal and the second pulse signal. These pulse signals are output from the pulse signal output terminal 2541. Moreover, there is an interval with a defined time between the first and second pulse signals (e.g., an opposite-logic signal, which may have a low logic level when the pulse signals have a high logic level), and the defined time is determined by the capacitance value of the capacitor 2642 and the resistance value of the resistor 2643).

From the detection stage entering the operating stage, the detection pulse generating module 2640 does not produce the pulse signal any more, and keeps the pulse signal output terminal 2541 on a low logic level potential. As described herein, the operating stage is the stage following the detection stage (e.g., following the time after the second pulse signal ends). The operating stage occurs when the LED tube lamp is at least partly connected to a power source, such as provided in a lamp socket. For example, the operating stage may occur when part of the LED tube lamp, such as only one side of the LED tube lamp, is properly connected to one side of a lamp socket, and part of the LED tube lamp is either connected to a high impedance, such as a person, and/or is improperly connected to the other side of the lamp socket (e.g., is misaligned so that the metal contacts in the socket do not contact metal contacts in the LED tube lamp). The operating stage may also occur when the entire LED tube lamp is properly connected to the lamp socket.

Referring to FIG. 19D, a detection determining circuit in accordance with certain embodiments is illustrated. An exemplary detection determining circuit 2670 includes a comparator 2671, and a resistor 2672. A negative input terminal of the comparator 2671 receives a reference logic level signal (or a reference voltage) Vref, a positive input terminal thereof is grounded through the resistor 2672 and is also coupled to a switch circuit coupling terminal 2581. Referring to FIGS. 19B and 19D, the signal flowing into the switch circuit 2580 from the installation detection terminal 2521 outputs to the switch circuit coupling terminal 2581 to the resistor 2672. When the current of the signal passing through the resistor 2672 reaches a certain level (for example, bigger than or equal to a defined current for installation, (e.g. 2A) and this makes the voltage on the resistor 2672 higher than the reference voltage Vref (referring to two end caps inserted into the lamp socket) the comparator 2671 produces a high logic level detection result signal and outputs it to the detection result terminal 2571. For example, when an LED tube lamp is correctly installed on a lamp socket, the comparator 2671 outputs a high logic level detection result signal at the detection result terminal 2571, whereas the comparator 2671 generates a low logic level detection result signal and outputs it to the detection result terminal 2571 when a current passing through the resistor 2672 is insufficient to make the voltage on the resistor 2672 higher than the reference voltage Vref (referring to only one end cap inserted into the lamp socket.) Therefore, in some embodiments, when the LED tube lamp is incorrectly installed on the lamp socket or one end cap thereof is inserted into the lamp socket but the other one is grounded by an object such as a human body, the current will be too small to make the comparator 2671 output a high logic level detection result signal to the detection result terminal 2571.

Referring to FIG. 19E, a schematic detection result latching circuit according to some embodiments of the present invention is illustrated. A detection result latching circuit 2660 includes a D flip-flop 2661, a resistor 2662, and an OR gate 2663. The D flip-flop 2661 has a CLK input terminal coupled to a detection result terminal 2571, and a D input terminal coupled to a driving voltage VCC. When the detection result terminal 2571 first outputs a low logic level detection result signal, the D flip-flop 2661 initially outputs a low logic level signal at a Q output terminal thereof, but the D flip-flop 2661 outputs a high logic level signal at the Q output terminal thereof when the detection result terminal 2571 outputs a high logic level detection result signal. The resistor 2662 is coupled between the Q output terminal of the D flip-flop 2661 and a reference voltage, such as ground potential. When the OR gate 2663 receives the first or second pulse signals from the pulse signal output terminal 2541 or receives a high logic level signal from the Q output terminal of the D flip-flop 2661, the OR gate 2663 outputs a high logic level detection result latching signal at a detection result latching terminal 2561. The detection pulse generating module 2640 only in the detection stage outputs the first and the second pulse signals to make the OR gate 2663 output the high logic level detection result latching signal, and thus the D flip-flop 2661 decides the detection result latching signal to be the high logic level or the low logic level the rest of the time, e.g. including the operating stage after the detection stage. Accordingly, when the detection result terminal 2571 has no high logic level detection result signal, the D flip-flop 2661 keeps a low logic level signal at the Q output terminal to make the detection result latching terminal 2561 also keep a low logic level detection result latching signal in the detection stage. On the contrary, once the detection result terminal 2571 has a high logic level detection result signal, the D flip-flop 2661 outputs and keeps a high logic level signal (e.g., based on VCC) at the Q output terminal. In this way, the detection result latching terminal 2561 keeps a high logic level detection result latching signal in the operating stage as well.

Referring to FIG. 19F, a schematic switch circuit according to some embodiments is illustrated. A switch circuit 2680 includes a transistor, such as a bipolar junction transistor (BJT) 2681, as being a power transistor, which has the ability of dealing with high current/power and is suitable for the switch circuit. The BJT 2681 has a collector coupled to an installation detection terminal 2521, a base coupled to a detection result latching terminal 2561, and an emitter coupled to a switch circuit coupling terminal 2581. When the detection pulse generating module 2640 produces the first and second pulse signals, the BJT 2681 is in a transient conduction state. This allows the detection determining circuit 2670 to perform the detection for determining the detection result latching signal to be a high logic level or a low logic level. When the detection result latching circuit 2660 outputs a high logic level detection result latching signal at the detection result latching terminal 2561, the BJT 2681 is in the conducting state to make the installation detection terminals 2521 and 2522 conducting. In contrast, when the detection result latching circuit 2660 outputs a low logic level detection result latching signal at the detection result latching terminal 2561 and the output from detection pulse generating module 2640 is a low logic level, the BJT 2681 is cut-off or in the blocking state to make the installation detection terminals 2521 and 2522 cut-off or blocking.

Since the external driving signal is an AC signal and in order to avoid the detection error resulting from the logic level of the external driving signal being just around zero when the detection determining circuit 2670 detects, the detection pulse generating module 2640 generates the first and second pulse signals to let the detection determining circuit 2670 perform two detections. So the issue of the logic level of the external driving signal being just around zero in a single detection can be avoided. In some cases, the time difference between the productions of the first and second pulse signals is not multiple times of half one cycle of the external driving signal. For example, it does not correspond to the multiple phase differences of 180 degrees of the external driving signal. In this way, when one of the first and second pulse signals is generated and unfortunately the external driving signal is around zero, it can be avoided that the external driving signal is again around zero when the other pulse signal is generated.

The time difference between the productions of the first and second pulse signals, for example, an interval with a defined time between both of them can be represented as following:

-   -   the interval=(X+Y)(T/2),     -   where T represents the cycle of an external driving signal, X is         a natural number, 0<Y<1, with Y in some embodiments in the range         of 0.05-0.95, and in some embodiments in the range of 0.15-0.85.

Furthermore, in order to avoid the installation detection module entering the detection stage from misjudgment resulting from the logic level of the driving voltage VCC being too small, the first pulse signal can be set to be produced when the driving voltage VCC reaches or is higher than a defined logic level. For example, in some embodiments, the detection determining circuit 2670 works after the driving voltage VCC reaching a high enough logic level in order to prevent the installation detection module from misjudgment due to an insufficient logic level.

According to the examples mentioned above, when one end cap of an LED tube lamp is inserted into a lamp socket and the other one floats or electrically couples to a human body or other grounded object, the detection determining circuit outputs a low logic level detection result signal because of high impedance. The detection result latching circuit stores the low logic level detection result signal based on the pulse signal of the detection pulse generating module, making it as the low logic level detection result latching signal, and keeps the detection result in the operating stage, without changing the logic value. In this way, the switch circuit keeps cutting-off or blocking instead of conducting continually. And further, the electric shock situation can be prevented and the requirement of safety standard can also be met. On the other hand, when two end caps of the LED tube lamp are correctly inserted into the lamp socket, the detection determining circuit outputs a high logic level detection result signal because the impedance of the circuit for the LED tube lamp itself is small. The detection result latching circuit stores the high logic level detection result signal based on the pulse signal of the detection pulse generating module, making it as the high logic level detection result latching signal, and keeps the detection result in the operating stage. So the switch circuit keeps conducting to make the LED tube lamp work normally in the operating stage.

In some embodiments, when one end cap of the LED tube lamp is inserted into the lamp socket and the other one floats or electrically couples to a human body, the detection determining circuit outputs a low logic level detection result signal to the detection result latching circuit, and then the detection pulse generating module outputs a low logic level signal to the detection result latching circuit to make the detection result latching circuit output a low logic level detection result latching signal to make the switch circuit cutting-off or blocking. As such, the switch circuit blocking makes the installation detection terminals, e.g. the first and second installation detection terminals, blocking. As a result, the LED tube lamp is in non-conducting or blocking state.

However, in some embodiments, when two end caps of the LED tube lamp are correctly inserted into the lamp socket, the detection determining circuit outputs a high logic level detection result signal to the detection result latching circuit to make the detection result latching circuit output a high logic level detection result latching signal to make the switch circuit conducting. As such, the switch circuit conducting makes the installation detection terminals, e.g. the first and second installation detection terminals, conducting. As a result, the LED tube lamp operates in a conducting state.

Thus, according to the operation of the installation detection module, a first circuit, upon connection of at least one end of the LED tube lamp to a lamp socket, generates and outputs two pulses, each having a pulse width, with a time period between the pulses. The first circuit may include various of the elements described above configured to output the pulses to a base of a transistor (e.g., a BJT transistor) that serves as a switch. The pulses occur during a detection stage for detecting whether the LED tube lamp is properly connected to a lamp socket. The timing of the pulses may be controlled based on the timing of various parts of the first circuit changing from high to low logic levels, or vice versa.

The pulses can be timed such that, during that detection stage time, if the LED tube lamp is properly connected to the lamp socket (e.g., both ends of the LED tube lamp are correctly connected to conductive terminals of the lamp socket), at least one of the pulse signals occurs when an AC current from a driving signal is at a non-zero level. For example, the pulse signals can occur at intervals that are different from half of the period of the AC signal. For example, respective start points or mid points of the pulse signals, or a time between an end of the first pulse signal and a beginning of the second pulse signal may be separated by an amount of time that is different from half of the period of the AC signal (e.g., it may be between 0.05 and 0.95 percent of a multiple of half of the period of the AC signal). During a pulse that occurs when the AC signal is at a non-zero level, a switch that receives the AC signal at the non-zero level may be turned on, causing a latch circuit to change states such that the switch remains permanently on so long as the LED tube lamp remains properly connected to the lamp socket. For example, the switch may be configured to turn on when each pulse is output from the first circuit. The latch circuit may be configured to change state only when the switch is on and the current output from the switch is above a threshold value, which may indicate a proper connection to a light socket. As a result, the LED tube lamp operates in a conducting state.

On the other hand, if both pulses occur when a driving signal at the LED tube lamp has a near-zero current level, or a current level below a particular threshold, then the state of the latch circuit is not changed, and so the switch is only on during the two pulses, but then remains permanently off after the pulses and after the detection mode is over. For example, the latch circuit can be configured to remain in its present state if the current output from the switch is below the threshold value. In this manner, the LED tube lamp remains in a non-conducting state, which prevents electric shock, even though part of the LED tube lamp is connected to an electrical power source.

It is worth noting that according to certain embodiments, the width of the pulse signal generated by the detection pulse generating module is between 10 μs to 1 ms, and it is used to make the switch circuit conducting for a short period when the LED tube lamp conducts instantaneously. In some embodiments, a pulse current is generated to pass through the detection determining circuit for detecting and determining. Since the pulse is for a short time and not for a long time, the electric shock situation will not occur. Furthermore, the detection result latching circuit also keeps the detection result during the operating stage (e.g., the operating stage being the period after the detection stage and during which part of the LED tube lamp is still connected to a power source), and no longer changes the detection result stored previously complying with the circuit state changing. A situation resulting from changing the detection result can thus be avoided. In some embodiments, the installation detection module, such as the switch circuit, the detection pulse generating module, the detection result latching circuit, and the detection determining circuit, could be integrated into a chip and then embedded in circuits for saving the circuit cost and layout space.

In embodiments of the present invention, a safety switch (which may be alternatively called a protective switch) is configured in the end cap for preventing leakage current and can connect the conductive pin 301 to the power supply module. For example, in connection with the previous figures, such a safety switch may be located between one of pins 501, 502, 503, or 504 (see FIGS. 13A-13D, for example), which may be external pins, and a part of a power supply module, such as a rectifier 510 or 540 of a power supply module. When the LED tube lamp is correctly/properly installed into or connected to a lamp socket or holder, the safety switch is triggered (e.g., the power supply module is electrically connected to the conductive pin 301). In this way, the end cap does not conduct electricity before the LED tube lamp is correctly installed into the lamp socket. And this provides the safety protection to the user for preventing the user from electric shock in case that one end of the LED tube lamp is inserted into the lamp socket but the other end is touched by the user's hand. In some embodiments, the safety switch is a (liquid) level switch triggered only through the LED tube lamp being correctly installed. And when the level switch is triggered (so that liquid flows to a preset position, for example, when moved by an actuator), the LED tube lamp works normally. A micro switch may be triggered by an actuator when the electrically conductive pin is plugged into the socket and the actuator is pressed. The end cap is configured to, likewise, turn on the micro switch and, directly or through a relay, close the circuit only when the electrically conductive pin is plugged into the socket.

In some embodiments, two safety switches are configured into two respective end caps on both ends of the LED tube lamp. Or, in other embodiments, only one safety switch is configured into one end cap, in which case, the end cap configured with the safety switch may be marked for reminding the user of first installing the unmarked end cap.

Referring to FIG. 20, a schematic structure of an LED tube lamp according to some embodiments of the present invention is illustrated. The LED tube lamp 100 may include one or more of the features described in the various above embodiments. The LED tube lamp 100 includes a lamp tube 1 and two end caps 3 (the proportion of the end caps 3 in relation to the lamp tube 1 schematized in FIG. 20 is exaggerated in order to highlight the structure of the end cap 3. In certain embodiments, the depth of each end cap 3 (e.g., length along a longitudinal direction of the lamp tube 1) is from 9 to 70 mm, and the axial length (e.g., along the longitudinal direction) of the lamp tube 1 is from 254 to 2000 mm, e.g., from 10 inches to 80 inches.) The end caps 3 are respectively configured at the both ends of the lamp tube 1. In one embodiment each end cap 3 includes an electrically conductive pin 301. In addition, one or both end caps may include an actuator 332, a micro switch 334, and all of part of a power supply module (e.g., a power supply module such as described previously). The end caps 3 may each include some or all of these components and in some embodiments do not include any additional components other than these components. When the LED tube lamp 100 is correctly/properly installed into a lamp socket or holder (not shown), the actuator 332 triggers the micro switch 334 for allowing the power supply module to electrically connect to externally input (commercial) electricity so as to light up the LED components (e.g., LED sources or LEDs as described in previous figures) in the LED tube lamp 100.

In accordance with an exemplary embodiment, the end cap 3 includes a housing, an electrically conductive pin 301, a power supply 5 and a safety switch. The safety switch is positioned between the electrically conductive pin 301 and the power supply 5. The end cap may be configured to contain the safety switch when the end cap is attached to an end of the lamp tube (e.g., by including a flange or other device that prevents the safety switch from moving outside the lamp tube). The safety switch may further include a micro switch 334 and an actuator 332. The end caps 3 are disposed on two ends of the glass tube 1 and are configured to turn on the safety switch—and make a circuit connecting, sequentially, main electricity coming from a socket of a lamp holder, the electrically conductive pin 301, the power supply 5 and the LED light assembly—when the electrically conductive pin 301 is plugged into the socket. The end cap 3 is configured to turn off the safety switch and open the circuit when the electrically conductive pin 301 is unplugged from the socket of the lamp holder. The lamp tube 1 is thus configured to minimize risk of electric shocks during installation and to comply with safety regulations.

In some embodiments, the safety switch directly—and mechanically—completes and breaks the circuit of the LED tube lamp. For example, an actuator can be used that moves when the lamp is properly plugged in, and as a result pushes a switch such as a micro-switch to cause the switch to electrically close, and therefore conduct electricity between components connected to one end of the switch and components connected to the other end of the switch. In other embodiments, the safety switch controls another electrical circuit, i.e. a relay, which in turn completes and breaks the circuit of the LED tube lamp. Some relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. For example, solid-state relays control power circuits with no moving parts, instead using a semiconductor device to perform switching.

Various safety switches, may be used for preventing an electric shock on a person who has improperly or incompletely installs the LED tube lamp into a lamp holder. These safety switches may include the micro switch 334 mentioned above. Examples of these safety switches, including various examples of actuators connected to a micro switch, can be seen in U.S. patent application Ser. No. 15/066,645, filed Mar. 10, 2016, and incorporated herein in its entirety by reference.

As shown in FIG. 21, an input terminal 3341 and an output terminal 3343 are respectively electrically connected to a hollow conductive pin (not shown) and a power supply module (not shown), correspondingly. Though not shown, an actuator, such as described above in connection with FIG. 20 and/or in U.S. patent application Ser. No. 15/066,645 may be included that, when moved, causes the micro switch 334 to be in a closed-circuit position. A bidirectional triode thyristor (TRIAC) 3345 is configured between the input terminal 3341 and the output terminal 3343, a resistor 3347 embodying a current-limiting device or component is electrically coupled to an a1 end of the micro switch 334, which has an a2 end electrically coupled to a trigger/control terminal of the TRIAC 3345. In one embodiment, the resistance of the resistor 3347 is from 1 Ohm to 10K Ohm, and in some cases, about 2K Ohm. In some embodiments, the current passing through the micro switch 334 in FIG. 21 is as small as about 0.1 A, compared to about 10 A, which is the value of the current passing through the embodiment of the micro switch 334 in FIG. 20. Accordingly, a micro switch 334 can be selected from a wider range of devices capable of tolerating the smaller current, and selecting from a wider range is conducive to reducing cost of the micro switch 334.

The safety switch could include a silicon controlled rectifier (SCR) as the current-limiting device in place of the resistor 3347; i.e., the safety switch may include the SCR, the TRIAC 3345, and the micro switch 334, wherein the micro switch 334 could comprise any micro switch in the embodiments mentioned above. The current-limiting device may be referred to herein as a current-limiting circuit. In one embodiment, the input terminal 3341 of the safety switch is electrically connected to any hollow conductive pin (e.g., external connection pin) of the LED tube lamp, and the output terminal 3343 thereof is electrically connected to the power supply module. Ends of the TRIAC 3345 are electrically coupled to the input terminal 3341 and the output terminal 3343, respectively. Further, the SCR is electrically coupled to the micro switch 334 in series. One end of the serially connected SCR and the micro switch 334 is electrically coupled to the control terminal of the TRIAC 3345, the other end of the serially connected SCR and the micro switch 334 is electrically coupled to the input terminal 3341.

When the micro switch 334 switches to an open-circuit position, the control terminal of the TRIAC 3345 is not coupled to the input terminal 3341. Meanwhile, the TRIAC 3345 is in a cutoff state so as to make the hollow conductive pin uncoupled to the power supply module. When the micro switch 334 is triggered/actuated and shorted (e.g., when it changes to a closed-circuit position), the current is transmitted from the input terminal 3341, the serially connected SCR and the micro switch 334 to the control terminal of the TRIAC 3345 to trigger the TRIAC 3345, causing it to conduct. Therefore, the hollow conductive pin 301 is coupled to the power supply module to make the LED tube lamp operate normally.

In the abovementioned embodiments with the safety switch by using the micro switch 334 only, an enormous instantaneous or transient current, for example bigger than 10 A, is an inrush flowing through the micro switch 334, the power supply module, and the LED components when the micro switch 334 is instantly triggered. Therefore, not only is the micro switch 334 likely to stand or endure a higher instantaneous current, but the volume thereof also is bigger. Further, the instantaneous current may damage the power supply module and the LED components. However, in some embodiments, the instantaneous current could be limited or restrained by the SCR or the resistor 3347 so as to lower the maximum current the micro switch 334 has to be able to withstand or endure, and simultaneously, the volume of the micro switch 334 and the cost can both be reduced. In this way, the current passing through the micro switch could be as low as about 0.1 A.

The LED tube lamps according to various different embodiments are described as above. With respect to an entire LED tube lamp, the features mentioned herein and in the embodiments may be applied in practice singly or integrally such that one or more of the mentioned features is practiced or simultaneously practiced.

According to certain embodiments of the power supply module, the external driving signal may be low frequency AC signal (e.g., commercial power), high frequency AC signal (e.g., that provided by a ballast), or a DC signal (e.g., that provided by a battery), input into the LED tube lamp through a drive architecture of single-end power supply or dual-end power supply. For the drive architecture of dual-end power supply, the external driving signal may be input by using only one end thereof as single-end power supply.

The LED tube lamp may omit the rectifying circuit when the external driving signal is a DC signal.

According to certain embodiments of the rectifying circuit in the power supply module, there may be a single rectifying circuit, or dual rectifying circuit. First and second rectifying circuits of the dual rectifying circuit are respectively coupled to the two end caps disposed on two ends of the LED tube lamp. The single rectifying circuit is applicable to the drive architecture of signal-end power supply, and the dual rectifying circuit is applicable to the drive architecture of dual-end power supply. Furthermore, the LED tube lamp having at least one rectifying circuit is applicable to the drive architecture of low frequency AC signal, high frequency AC signal or DC signal.

The single rectifying circuit may be a half-wave rectifier circuit or full-wave bridge rectifying circuit. The dual rectifying circuit may comprise two half-wave rectifier circuits, two full-wave bridge rectifying circuits or one half-wave rectifier circuit and one full-wave bridge rectifying circuit.

According to certain embodiments of the pin in the power supply module, there may be two pins in a single end (the other end has no pin), two pins in corresponding end of two ends, or four pins in corresponding end of two ends. The designs of two pins in single end two pins in corresponding end of two ends are applicable to signal rectifying circuit design of the of the rectifying circuit. The design of four pins in corresponding end of two ends is applicable to dual rectifying circuit design of the of the rectifying circuit, and the external driving signal can be received by two pins in only one end or in two ends. And the pins may alternatively be called input terminals.

According to certain embodiments of the filtering circuit of the power supply module, there may be a single capacitor, or n filter circuit. The filtering circuit filers the high frequency component of the rectified signal for providing a DC signal with a low ripple voltage as the filtered signal. The filtering circuit also further comprises the LC filtering circuit having a high impedance for a specific frequency for conforming to current limitations in specific frequencies of the UL standard. Moreover, the filtering circuit according to some embodiments further comprises a filtering unit coupled between a rectifying circuit and the pin(s) for reducing the EMI.

According to certain embodiments of the LED lighting module, the LED lighting module may comprise the LED module and the driving circuit, or only the LED module. The LED module may be connected with a voltage stabilization circuit for preventing the LED module from overvoltage. The voltage stabilization circuit may be a voltage clamping circuit, such as zener diode, DIAC and so on. When the rectifying circuit has a capacitive circuit, in some embodiments, two capacitors are respectively coupled between corresponding two pins in two end caps and so the two capacitors and the capacitive circuit as a voltage stabilization circuit perform a capacitive voltage divider.

In some embodiments, if there are the LED module and the driving circuit in the LED lighting module, the driving circuit may be a buck converter, a boost converter, or a buck-boost converter. The driving circuit stabilizes the current of the LED module at a defined current value, and the defined current value may be modulated based on the external driving signal. For example, the defined current value may be increased with the increasing of the level of the external driving signal and reduced with the reducing of the level of the external driving signal. Moreover, a mode switching circuit may be added between the LED module and the driving circuit for switching the current from the filtering circuit directly or through the driving circuit inputting into the LED module.

According to certain embodiments of the LED module of the power supply module, the LED module comprises plural strings of LEDs connected in parallel with each other, wherein each LED may have a single LED chip or plural LED chips emitting different spectrums. Each LEDs in different LED strings may be connected with each other to form a mesh connection.

Having described at least one of the embodiments with reference to the accompanying drawings, it will be apparent to those skills in the art that the disclosure is not limited to those precise embodiments, and that various modifications and variations can be made in the presently disclosed system without departing from the scope or spirit of the disclosure. It is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents. Specifically, one or more limitations recited throughout the specification can be combined in any level of details to the extent they are described to improve the LED tube lamp. These limitations include, but are not limited to, a shock-preventing safety switch.

Though certain documents are described as being incorporated by reference herein, and the subject matter of those applications has been incorporated by reference herein, the following claims should be interpreted according to claim construction in view of the terminology and language used in this application. In addition, while various aspects of the inventive concept have been described with reference to exemplary embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the inventive concept. Therefore, it should be understood that the disclosed embodiments are not limiting, but illustrative. 

What is claimed is:
 1. A light emitting diode (LED) tube lamp, comprising: a lamp tube, having a first pin and a second pin at a first end of the lamp tube and a third pin at a second end of the lamp tube, for receiving an external driving signal; a rectifying circuit for rectifying the external driving signal to produce a rectified signal, the rectifying circuit comprising a first rectifying circuit coupled to the first and second pins, wherein the first rectifying circuit comprises diodes; the rectifying circuit comprising a second rectifying circuit coupled to the third pin, wherein the second rectifying circuit comprises two diodes, and a common node between the two diodes of the second rectifying circuit connects an anode and a cathode respectively of the two diodes of the second rectifying circuit; an EMI reducing element coupled between the common node between the two diodes of the second rectifying circuit, and the third pin; and a filtering circuit coupled to the rectifying circuit, for filtering the rectified signal to produce a filtered signal for driving an LED module to emit light, the filtering circuit comprising a capacitor connected in parallel with an LED unit included in the LED module, wherein the LED module is configured to receive the filtered signal for emitting light, and the filtering circuit is coupled between an anode of one of the two diodes of the second rectifying circuit, and a cathode of the other diode of the two diodes of the second rectifying circuit.
 2. The LED tube lamp according to claim 1, wherein the diodes of the first rectifying circuit constitute a full-wave rectifier circuit.
 3. The LED tube lamp according to claim 1, wherein the EMI reducing element comprises a capacitor to reduce the EMI associated with the external driving signal received at one or more of the pins.
 4. The LED tube lamp according to claim 3, wherein the capacitor of the EMI reducing element is a current-limiting element positioned to limit a current flowing through the LED unit.
 5. The LED tube lamp according to claim 1, wherein the diodes of the first rectifying circuit comprise four diodes, a first common node between two of the four diodes connects an anode and a cathode respectively of the two of the four diodes, and a second common node between the other two of the four diodes connects an anode and a cathode respectively of the other two of the four diodes.
 6. The LED tube lamp according to claim 5, wherein the filtering circuit further comprises an EMI reducing element coupled between the first and second common nodes.
 7. The LED tube lamp according to claim 6, wherein the EMI reducing element of the filtering circuit comprises a capacitor coupled between the first and second pins to reduce the EMI associated with the external driving signal received at the first and second pins.
 8. The LED tube lamp according to claim 1, further comprising a fourth pin at the second end of the lamp tube, wherein the EMI reducing element comprises two inductors connected to the third pin and the fourth pin respectively, and comprises a capacitor; and a connecting node between the two inductors is coupled to the capacitor of the EMI reducing element.
 9. The LED tube lamp according to claim 1, wherein the EMI reducing element comprises an inductor connected between the third pin and the second rectifying circuit; and the LED tube lamp further comprises another EMI reducing element comprising an inductor connected between the first or second pin and the first rectifying circuit.
 10. The LED tube lamp according to claim 1, further comprising a fourth pin at the second end of the lamp tube, wherein the EMI reducing element comprises two inductors connected to the third pin and the fourth pin respectively; and the LED tube lamp further comprises another EMI reducing element comprising two inductors respectively connected between the first pin and the first rectifying circuit and connected between the second pin and the first rectifying circuit.
 11. The LED tube lamp according to claim 1, wherein the EMI reducing element comprises a fuse connected between the third pin and the second rectifying circuit.
 12. The LED tube lamp according to claim 1, further comprising another EMI reducing element comprising a fuse connected between the first or second pin and the first rectifying circuit. 